JOURNAL OF LATEX CLASS FILES, VOL. 1, NO. 11, NOVEMBER 2002

1

How to Use the IEEEtran LATEX Class
Michael Shell, Member, IEEE
(Invited Paper)
Abstract— This article describes how to use the IEEEtranclass with LATEX to produce high quality typeset papers thatare suitable for submission to the Institute of Electrical andElectronics Engineers (IEEE). IEEEtran can produce conference,
journal and technical note (correspondence) papers with asuitable choice of class options. This document was produced
using IEEEtran in journal mode. Conference and correspondence
papers typically use a subset of the commands discussed here.
Index Terms— Class, IEEEtran, LATEX, paper, style, template,
typesetting.

I. I NTRODUCTION
ITH a recent IEEEtran class file, a computer running LATEX, and a basic understanding of the LATEX
language, an author can produce professional quality typeset
research papers very quickly, inexpensively, and with minimal
effort. The purpose of this article is to serve as a user guideof IEEEtran LATEX class and to document its unique featuresand behavior.
This document applies to version 1.6b and later of IEEEtran.
Prior versions do not have all of the features described here.
IEEEtran will display the version number on the user’s console
when a document using it is being compiled. The latest versionof IEEEtran and its support files can be obtained from IEEE’s
web site [2], or CTAN [1]. This latter site may have some
additional material, such as beta test versions and files related
to non-IEEE uses of IEEEtran.
Complimentary to this document are the files1 bare_con
f.tex and bare_jrnl.tex which are “bare bones” example(template) files of a conference and a journal paper, respectively. Authors can quickly obtain a functional document byusing these files as starters for their own work.
It is assumed that the reader has at least a basic working
knowledge of LATEX. Those so lacking are strongly encouraged
to read some of the excellent literature on the subject [3]. General support for LATEX related questions can be obtained in theinternet newsgroup comp.text.tex. There is also a searchable
list of frequently asked questions for this newsgroup [4].
Please note that the appendices sections contain information
on installing the IEEEtran class file as well as tips on how to
avoid commonly made mistakes.

W

Manuscript created February 25, 2002; revised November 18, 2002. This
work was supported by the IEEE. The opinions expressed here are entirelythat of the author. No warranty is expressed or implied. User assumes all risk.
M. Shell is with the Georgia Institute of Technology.
Email: mshell@ece.gatech.edu See [1] for current contact information.
1 Note that it is the convention of this document not to hyphenate command,
file or in-main-text URL names and to display them in typewriter font.
Within such constructs, spaces are not implied at a line break and will be
explicitly carried into the beginning of the next line. This behavior is nota feature of IEEEtran, but is used here to illustrate computer commands
verbatim.

II. C LASS O PTIONSThere are a number of class options that can be used tocontrol the overall mode and behavior of IEEEtran. These are
specified in the traditional LATEX way. For example,\documentclass[9pt,technote]{IEEEtran}

is used with correspondence (technote) papers. The various
categories of options will now be discussed. For each category,the default option is shown in bold. The user must specify an
option from each category in which the default is not the one
desired. The various categories are totally orthogonal to eachother — changes in one will not affect the defaults in theothers.
A. 9pt, 10pt, 11pt, 12pt
There are four possible values for the normal text size. 10pt
is used by the vast majority of papers. The two exceptions aretechnote papers, which use 9pt text, and the initial submissions
to some conferences which use 11pt.
B. draft, draftcls, draftclsnofoot, final
IEEEtran provides for three draft modes as well as thenormal final mode. The draft modes provide a larger line
spacing to allow for editing comments. The standard draft
option puts every package used in the document into draft
mode. With most graphics packages, this has the effect of
disabling the rendering of figures. If this is not desired, one
can use the draftcls option instead to yield a draft mode thatwill be confined within the IEEEtran class so that figures will
be included as normal. draftclsnofoot is like draftcls, but does
not display the word “DRAFT” along with the date at the footof each page. When using one of the draft modes, most users
will also want to select the onecolumn option.
C. conference, journal, technote, peerreview, peerreviewca
IEEEtran offers five major modes to encompass conference,
journal, correspondence (technote) and peer review papers.
Journal and technote modes will produce papers very similar
to those that appear in many IEEE Transactions journals.
When using technote, most users should also select the 9pt
option. The peerreview mode is much like the journal mode,
but produces a single-column cover page (with the title, authornames and abstract) to facilitate anonymous peer review. The
title is repeated (without the author names or abstract) on thefirst page after the cover page.2 Papers using the peer review
2 A blank page may be inserted after the cover page when using the twoside(duplex printing) option so that the beginning of the paper does not appear
on the back side of the cover page.

0000–0000/00$00.00 c 2002 IEEE

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options require an \IEEEpeerreviewmaketitle command(in addition to and after the traditional \maketitle) to be
executed at the place the cover page is to end — usuallyjust after the abstract. This command will be silently ignoredwith the non-peerreview modes. See the bare template files
for an example of the placement of this command. The
peerreviewca mode is like peerreview, but allows the authorname information to be entered and formatted as is donein conference mode (see Section III-B.2 for details) so that
author affiliation and contact information is more visible tothe editors.
1) Conference mode details: Conference mode makes anumber of significant changes to the way IEEEtran behaves.
• The figure captions are centered.
• The \author text is placed within a tabular environment
to allow for multicolumn formatting of author names andaffiliations. Several commands are enabled to facilitate
this formatting (see Section III-B.2 for details).
• The spacing after the authors’ names is reduced. So is
the spacing around the section names.
• The special paper notice (if used) will appear between theauthor names and the title (not after as with journals).
• The margins are increased as the height of the text is
reduced to about 9.25in. In particular, the bottom margin
will become larger than that of the top as IEEE wants
extra clearance at the bottom. The text height will not be
exactly 9.25in, but will vary slightly with the normal fontsize to ensure an integer number of lines in a column.
• Headings and page numbers are not displayed in the headers or footers. This, coupled with symmetric horizontal
margins, will mean that there will not be a noticeable
difference between one and two sided options.
• The following commands are intentionally disabled: \thanks, \PARstart, \keywords, \biography, \biogr
aphynophoto, \pubid, \pubidadjcol, \IEEEmember
ship, and \IEEEaftertitletext. If needed, they canbe reenabled by issuing the command: \IEEEoverridecommandlockouts.
• Various reminder (related to camera ready work) andwarning notices are enabled.
D. letterpaper, a4paper
IEEEtran supports both US letter (8.5in × 11in) and A4(210mm × 297mm) paper sizes. Since IEEE uses US letter,authors should select the letterpaper option before submitting
their work to IEEE. The main purpose of the a4paper option
is to allow authors outside the US to print their work on A4
paper. Changing the paper size will not alter the typesettingof the document — only the margins will be affected. In
particular, documents using the a4paper option will have
reduced side margins (A4 is narrower than US letter) and alonger bottom margin (A4 is longer than US letter). For bothcases, the top margins will be the same and the text will be
horizontally centered.
Note that authors should ensure that all post-processing(ps, pdf, etc.) uses the same paper specification as the .tex document. Problems here are by far the number one reason
for incorrect margins. See Appendix II for more details.

JOURNAL OF LATEX CLASS FILES, VOL. 1, NO. 11, NOVEMBER 2002

For those users who are doing their own binding, thecommand \overrideIEEEmargins can be issued in the
document preamble to provide a wider margin on the bindingedge. This command will have no effect in draft mode andshould not be used for work that is to be submitted to theIEEE.
E. oneside, twoside
These options control whether the layout follows that ofsingle sided or two sided (duplex) printing. Because the side
margins are normally centered, the main notable difference isin the format of the running headings.
F. onecolumn, twocolumn
These options allow the user to select between one and twocolumn text formatting. Since IEEE always uses two column
text, the onecolumn option is of interest only with draft papers.
G. nofonttune
IEEEtran normally alters the default interword spacing to
be like that used in IEEE publications. The result is text that
requires less hyphenation and generally looks more pleasant,especially for two column text. The nofonttune option will
disable the adjustment of these font parameters. This option
should be of interest only to those who are using fonts
specifically designed or modified for use with IEEE work.
III. T HE T ITLE PAGE
The parts of the document unique to the title area are createdusing the standard LATEX command \maketitle. Before thiscommand is called, the author must declared all of the text
objects which are to appear in the title area.
A. Paper Title
The paper title is declared like:\title{A Heuristic Coconut-based Algorithm}

in the standard LATEX manner. Line breaks (\\) may be used
to equalize the length of the title lines.
B. Author Names
The name and associated information is declared with the\author command. \author behaves slightly differently

depending on the document mode.
1) Names in Journal/Technote Mode: A typical \authorcommand for a journal or technote paper looks something likethis:\author{Michael˜Shell,˜\IEEEmembership{Member,˜IEEE,} John˜Doe,˜\IEEEmembership{Fellow,˜OSA,} and˜Jane˜Doe,˜\IEEEmembership{Life˜Fellow,˜IEEE}%\thanks{Manuscript received January 20, 2002; revise
d January 30, 2002. This work was supported by the IE
EE.}%\thanks{M. Shell is with the Georgia Institute of Te
chnology.}}SHELL: HOW TO USE THE IEEETRAN LATEX CLASSThe \IEEEmembership command is used to produce theitalic font that indicates the authors’ IEEE membership status. The \thanks command produces the “first footnotes.”
Because the LATEX \thanks was not designed to containmultiple paragraphs, one will have to use a separate \thanks for each paragraph. However, if needed, regular line breaks(\\) can be used within \thanks. In order to get proper line
breaks and spacing, it is important to correctly use and control
the spaces within \author. Use nonbreaking spaces (˜) toensure that name/membership pairs remain together. A minor,
but easy, mistake to make is to forget to prevent unwanted
spaces from getting between commands which use delimited({}) arguments. Note the two % which serve to prevent thecode line break on lines ending in a } from becoming an
unwanted space. Such a space would not be ignored as an
end-of-line space because, technically, the last \thanks isthe final command on the line. “Phantom” spaces like thesewould append to the end of the last author’s name, causing
the otherwise centered name line to shift very slightly to theleft.
2) Names in Conference Mode: The author name area
is more complex when in conference mode because it also
contains the authors’ affiliations. For this reason, when in
conference mode, the contents of \author{} are placed intoa modified tabular environment. The commands \authorbl
ockN{} and \authorblockA{} are also provided so that it
is easy to correctly format the author names and affiliations,
respectively. For papers with three or less affiliations, a multicolumn format is preferred:\author{\authorblockN{Michael Shell}\authorblockA{School of Electrical and\\Computer Engineering\\
Georgia Institute of Technology\\
Atlanta, Georgia 30332--0250\\
Email: mshell@ece.gatech.edu}\and\authorblockN{Homer Simpson}\authorblockA{Twentieth Century Fox\\
Springfield, USA\\
Email: homer@thesimpsons.com}\and\authorblockN{James Kirk\\
and Montgomery Scott}\authorblockA{Starfleet Academy\\
San Francisco, California 96678-2391\\
Telephone: (800) 555--1212\\
Fax: (888) 555--1212}}

Use \and to separate the affiliation columns. The columns
will automatically be centered with respect to each other andthe side margins.
If there are more than three authors and/or the text is too
wide to fit across the page, use an alternate format:\author{\authorblockN{Michael Shell\authorrefmark{1}, Homer Simpson\authorrefmark{2}, James Kirk\authorr
efmark{3}, Montgomery Scott\authorrefmark{3} and Eldon Tyrell\authorrefmark{4}}\authorblockA{\authorrefmark{1}School of Electrical and Computer Engineering\\
Georgia Institute of Technology, Atlanta, Georgia 30
332--0250\\
Email: mshell@ece.gatech.edu}\authorblockA{\authorrefmark{2}Twentieth Century Fox, Springfield, USA\\
Email: homer@thesimpsons.com}

3\authorblockA{\authorrefmark{3}Starfleet Academy, Sa
n Francisco, California 96678-2391\\
Telephone: (800) 555--1212, Fax: (888) 555--1212}\authorblockA{\authorrefmark{4}Tyrell Inc., 123 Repl
icant Street, Los Angeles, California 90210--4321}}

The \authorrefmark{} command will generate a footnote
symbol corresponding to the number in its argument. Use thisto link the author names to their respective affiliations. It is
not necessary prevent spaces from being between the \authorblock’s because each block starts a new group of linesand LATEX will ignore spaces at the very end and beginning oflines.
C. Running Headings
The running headings are declared with the \markboth{}{} command. The first argument contains the journal nameinformation and the second contains the author name and paper
title. For example:\markboth{Journal of Quantum Telecommunications,˜Vol.˜1, No.˜1,˜January˜2025}{Shell \MakeLowercase{\text
it{et al.}}: A Novel Tin Can Link}

Note that because the text in the running headings is automatically capitalized, the \MakeLowercase{} command must be
used to obtain lower case text. The second argument is used
as a page heading only for the odd number pages after thetitle page for two sided (duplex) journal papers. This page issuch an example. Technote papers do not utilize the second
argument. Conference papers do not have running headings,
so \markboth{}{} has no effect when in conference mode.
Authors should not put any name information in the headings(if used) of anonymous peer review papers.
D. Publication ID Marks
Publication ID marks can be placed on the title page ofjournal and technote papers via the \pubid{} command. The
title page of this document has a publication ID that was madewith:\pubid{0000--0000/00\$00.00˜\copyright˜2002 IEEE}

Although authors do not yet have a valid publication ID at
the time of paper submission, \pubid{} is useful because it
provides a means to see how much of the title page text area
will be unavailable in the final publication. This is especially
important in technote papers because, in some journals, thepublication ID space can consume more than one text line.
If \pubid{} is used, a second command, \pubidadjcol
must be issued somewhere in the second column of the title
page. This is needed because LATEX resets the text height at
the beginning of each column. \pubidadjcol “pulls up” thetext in the second column to prevent it from blindly running
into the publication ID.
Publication IDs are not to be placed by the author on
camera ready conference papers so \pubid{} is disabled inconference mode. Instead the bottom margin is automaticallyincreased by IEEEtran when in conference mode to give IEEE
room for such marks at the time of publication. In draft mode,the publisher ID mark will not be printed at the bottom of thetitlepage, but room will be cleared for it.

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JOURNAL OF LATEX CLASS FILES, VOL. 1, NO. 11, NOVEMBER 2002

E. Special Paper Notices

A. Initial Drop Cap Letter

Special paper notices, such as for invited papers, can be
declared with:

The first letter of a journal paper is a large, capital, oversized
letter which descends one line below the baseline. Such a
letter is called a “drop cap” letter. The other letters in the firstword are rendered in upper case. This effect can be accurately
produced using the IEEEtran command \PARstart{}{}. The
first argument is the first letter of the first word, the second
argument contains the remaining letters of the first word. The
drop cap of this document was produced with:\specialpapernotice{(Invited Paper)}Special paper notices in journal and technote papers appear
between the author names and the main text. The title pageof this document has an example. For conference papers, thespecial paper notice is placed between the title and the authornames.
Much more rarely, there is sometimes a need to gain accessto the space across both columns just above the main text. For
instance, a paper may have a dedication [5]. IEEEtran provides
the command \IEEEaftertitletext{} which can be used
to insert text or to alter the spacing between the title area andthe main text:\IEEEaftertitletext{\vspace{-1\baselineskip}}

Authors should be aware that IEEEtran carefully calculates
the spacing between the title area and main text to ensure thatthe main text height of the first page always is equal to an
integer number of normal sized lines. Failure to do this canresult in underfull vbox errors and paragraphs being “pulled
apart” in the second column of the first page if there isn’t
any rubber lengths (such as those around section headings) inthat column. The contents of \IEEEaftertitletext{} areintentionally allowed to bypass this “dynamically determined
title spacing” mechanism, so authors may have to manually
tweak the height (by a few points) of the \IEEEaftertitle
text{} contents (if used) to avoid an underfull vbox warning.
IV. A BSTRACT AND I NDEX T ERMS

\PARstart{W}{ith}Note that some journals will also render the second word inupper case — especially if the first word is very short. For
more usage examples, see the bare_jrnl.tex template file.
VI. C ITATIONS
Citations made with the \cite{} command as usual.
IEEEtran will produce citation numbers that are individually
bracketed in IEEE style. (“[1], [5]” as opposed to the morecommon “[1, 5]” form.) The base IEEEtran does not sort or
produce “ranges” when there are three or more consecutive
citation numbers. However, IEEEtran pre-defines some format
control macros to facilitate easy use with the LATEX cite.sty
package [6]. So, all an author has to do is to call cite.sty:\usepackage{cite}

and the citation numbers will automatically be sorted andranged IEEE style.
Note that, if needed, the cite.sty’s \cite{} command willautomatically add a leading space. i.e., “(\cite{mshell01})” will become like “( [1]).” If this behavior is not desired,
use the cite package’s noadjust option (cite.sty V3.8 and later)which will turn off the added spaces:\usepackage[noadjust]{cite}

The abstract is generally the first part of a paper after \maketitle. The abstract text is placed within the abstract
environment:\begin{abstract}
We propose ...
\end{abstract}

Journal and technote papers also have a list of key words(index terms) which can be declared with:\begin{keywords}
Broad band networks, quality of service, WDM.
\end{keywords}\cite{} also allows for an optional note. e.g., \cite[Th.
7.1]{mshell01}. If the \cite{} with note has more than

one reference, the note will be applied to the last of the listed
references. It is generally desirable that if a note is given, only
one reference should be listed in that \cite{}.
VII. E QUATIONS
Equations are created using the traditional equation environment:\begin{equation}\label{eqn_example}
x = \sum\limits_{i=0}ˆ{z} 2ˆ{i}Q\end{equation}

V. S ECTIONS
which yields
Sections and their headings are declared in the usual LATEX
fashion via \section{}, \subsection{}, \subsubsection{}, and \paragraph{}. The numbering for these sections isin upper case Roman numerals, upper case letters, Arabic numerals and lower case letters, respectively. The \paragraph{} section is not allowed for technotes as they generally are notpermitted to have such a deep section nesting depth. If needed,\paragraph{} can be restored by issuing the command \setcounter{secnumdepth}{4} in the document preamble.

x=

z
X

2i Q.

(1)

i=0

Use the displaymath environment instead if no equation
number is desired. When referring to equations, articles inIEEE publications do not typically use the word “equation,”but rather just enclose the equation number in parentheses,
e.g.,... as can be seen in (\ref{eqn_example}).

SHELL: HOW TO USE THE IEEETRAN LATEX CLASS

5IEEE’s two column format puts serious constraints on how
wide an equation can be. So, a fair portion of the effort informatting equations usually has to be devoted to properly
breaking them. It is the author’s responsibility to ensurethat all equations fit into the given column width. In rare
circumstances, it is possible to have a few equations that span
both columns (see Section IX-C.1), but the vast majority ofover-length equations have to be broken across multiple lines.
VIII. M ULTI - LINE E QUATIONSPerhaps the most convenient and popular way to produce multiline equations is LATEX 2ε ’s eqnarray environment.
However, eqnarray has several serious shortcomings:
1) the use of 2×\arraycolsep for a column separation
space does not provide natural math spacing in thedefault configuration;2) column definitions cannot be altered;3) is limited to three alignment columns;4) column alignment cannot be overridden within individual cells.
There are a number of vastly superior packages for formatting multiline mathematics. Perhaps the most popular is theamsmath package [7]. Amsmath is a comprehensive work
which contains many helpful tools besides enhanced multilinealignment environments. So, all authors should give serious
consideration to its use — regardless of what they use to
generate aligned equations. One thing to be aware of is that,upon loading, amsmath will configure LATEX to disallow page
breaks within multiline equations (even within non-amsmath
defined environments). The philosophy here is that author
should manually insert breaks where desired so as to ensurethat breaks occur only at acceptable points. To restore IEEEtran’s ability to automatically break within multiline equations,load amsmath like:\usepackage{amsmath}\interdisplaylinepenalty=2500

Another extremely powerful set of alignment tools, oneof which is a totally rewritten eqnarray environment, isprovided by mathenv.sty which is part of Mark Wooding’s
MDW Tools [8].
Finally, IEEEtran provides a fully integrated custom IEEEeqnarray family of commands (see Appendix VI) that aredesigned to have almost universal applicability for manydifferent types of alignment situations.
Nevertheless, it is instructive to show a simple example
using the standard eqnarray in order to explain some of
the fine points of math spacing under LATEX. As shown in
Table I, TEX normally draws from four different spacings whentypesetting mathematics. In order to produce precision (andcorrect) mathematical alignments, it is crucial to understandhow to control such spacing. Consider a multiline equation
Z = x1 + x2 + x3 + x4 + x5 + x6
+a + b+a + b
+a+b

(1)
(2)
(3)

+a+b

(4)

TABLE IM ATH S PACINGS U SED BY LATEX
Size

Width

Cmd.

Used for

Examplesmall
mediumlarge
negative small

1/6 em

\,
\:
\;
\!

symbolsbinary operators
relational operators
misc. uses

ab
a+b
a=b
ab

2/9 em
5/18 em−1/6 em(in typical IEEE style) which was produced by\setlength{\arraycolsep}{0.0em}\begin{eqnarray}Z&{}={}&x_1 + x_2 + x_3 + x_4 + x_5 + x_6\nonumber\\&&+a + b\\&&+{}a + b\\&&{}+a + b\\&&{+}\:a + b\end{eqnarray}\setlength{\arraycolsep}{5pt}Lines one through four show some possible ways the + a + bline could be implemented.3 Only number four is the correct
way for most IEEE purposes. In TEX’s math mode, spacing
around operators can be inhibited by enclosing them withinbraces (e.g., {=}) or forced by surrounding them with “emptyords” (e.g., {}={}). It is important to understand that theempty ords do not have width themselves. However, theirpresence causes TEX to place space around the operators as if
they were “next to something.” With this in mind, the first stepin the example is to set \arraycolsep to zero to prevent eq
narray from putting in the unwanted, artificial, inter-column
spacing. Placing empty ords around the equal sign then forces
the correct natural spacing. Alternatively, \arraycolsep
could have been set to 0.14 em and the empty ords around theequal sign eliminated.4 It is important to remember to restore\arraycolsep to its default value of 5 pt after the eqn
array is complete as other environments (such as array)depend on it.
The first line is incorrect because a is being indicated asa positive quantity rather than something that must be added
to the previous line. (i.e., the + is being treated as a unary,rather than a binary, operator.) In line two, adding an empty
ord to the right side of the plus sign does nothing, except
to demonstrate that empty ords have zero width. Adding an
empty ord to the left side of the plus sign (line three) does
engage binary spacing, but causes an unwanted5 right shiftof the line. Finally, manually adding a medium space to theright side only of the plus sign in line four does the trick. The
suppression of automatic spacing around the plus sign ({+}) is
unneeded in this case, but may be required in other alignment
environments that “expand” such operators by default.
Another way around the spacing problem is to use only
two alignment columns (as is done by amsmath.sty’s \align). e.g., in the previous example, “Z =” would be contained
3 In this absurd example, the equation numbering system is used to identify
lines.
4 This assumes that 1 em in the text font has the same width as 1 em in themath font. For the standard fonts, this is indeed the case.
5 IEEE normally wants all of the lines left aligned, but there are cases whensuch an indention may be desirable.

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JOURNAL OF LATEX CLASS FILES, VOL. 1, NO. 11, NOVEMBER 2002

TABLE IIin the first column.
A. Cases Structures
Incidentally, the numcases (or subnumcases) environments in Donald Arseneau’s cases.sty package [9] should be
used when “cases” structures in which each branch can bereferenced with a different equation (or subequation) number
are needed:x,
for x ≥ 0
(2a)
|x| =
−x,
for x < 0(2b)because those built from the array or amsmath cases environments will have a single equation number that encompasses
both branches.
IX. F LOATING S TRUCTURES
A. Figures
Figures handled in the standard LATEX manner. For example:\begin{figure}\centering\includegraphics[width=2.5in]{myfigure}\caption{Simulation Results}\label{fig_sim}\end{figure}

Note that (1) figures should be centered via the LATEX \centering command. This is a better approach than using the center environment which adds unwanted vertical spacing; (2)the caption follows the graphic; and (3) any labels must be
declared after (or within) the caption command.
When referencing figure numbers in the main text (via\ref{}), IEEE uses the abbreviation “Fig.” rather than “Figure”.
The \includegraphics command is the modern, preferred, way of including images and provides a flexible interface that makes it easy to scale graphics to size. To use it,
the graphics or graphicx (recommended) must first be loaded.
It is strongly recommended that authors be familiar with thegraphics package documentation [10] as well as Keith Reckdahl’s excellent Using Imported Graphics in LATEX 2ε [11]. The
reader is reminded that the “draftcls” or “draftclsnofoot”, not“draft”, class option must be selected in order to get draft
papers with visible figures.
As explained in Appendix IV, Encapsulated PostScript(EPS) is the preferred graphics format for LATEX work. Furthermore, the user’s drawing/graphing application should becapable of outputing directly in EPS vector form (which will
not degrade or pixelize when magnified) — although photos
will likely have to be in (EPS) bitmap form.
The psfrag package [12] might also be of interest. Psfrag
allows the user to “go into” an EPS graphic and replace text
strings contained in it with real LATEX code! In this manner,
LATEX’s extensive support of mathematical symbols and fonts
can be extended to figures made with applications with moremodest glyph support. Using psfrag does require the use of
the dvips DVI to PostScript conversion step (not pdfLATEX6 )6 pdfLAT X users currently have to “preprocess” their figures by importingEthem into a dummy document using psfrag, running LATEX followed by dvips,
then converting the PostScript output to a PDF graphic for importation into
the main document which is then processed by pdfLATEX.

A S IMPLE E XAMPLE TABLE
First

Next

1.0

2.0

as some of the features of the PostScript language have to be
utilized. There is additional usage information on psfrag in the
Using Imported Graphics in LATEX 2ε guide [11].
B. Tables
Tables are handled in a similar fashion, but with a few
notable differences. For example, the code
\begin{table}\renewcommand{\arraystretch}{1.3}\caption{A Simple Example Table}\label{table_example}\centering\begin{tabular}{c||c}\hline\bfseries First & \bfseries Next\\\hline\hline
1.0 & 2.0\\\hline\end{tabular}\end{table}

results in Table II. Note that IEEE places table captions before
the tables. Within the table environment, the default text size
is footnotesize which is what IEEE typically uses for tables.
When using the tabular environment to construct tables, it isusually a good idea to increase the value of \arraystretch
above unity to “open up” the table rows a tad. Also, IEEE often
uses tables with “open sides,” (without vertical lines alongeach side) although the “closed side” form (e.g., Table I) is
more commonly used for the tables within this document.
Unfortunately, the standard LATEX 2ε tabular environment
has a number of shortcomings. Two notable problems are (1)the corners where lines meet are improperly formed; and (2) it
is not very flexible in terms of user control. For these reasons,authors are urged to look into some of the other packages
for making tables. A good one that provides revised “drop-in
replacements” for both the tabular and array environments is
Frank Mittelbach’s and David Carlisle’s array package [13].
Even more powerful (and complex) is the tabular and arrayenvironments provided by the mdwtab.sty package which ispart of Mark Wooding’s MDW Tools [8].
As an alternative, IEEEtran offers the IEEEeqnarraybox
command which can also be used to produce tables7 of highquality. See Appendix VI for more details.
1) Footnotes Within Tables: Footnotes normally cannot be
placed directly within some commands and environments
such as \parbox, and tabular, etc., because they become“trapped” inside. One way around this is to split the place
the footnote marker (\footnotemark) is located (within thetable) from where the footnote text itself is declared (outsideof the table using \footnotetext).
7 Table I was made using this command.

SHELL: HOW TO USE THE IEEETRAN LATEX CLASS

7TABLE IIIT HE S KEWING A NGLES (β) FOR Mu(H) + X2
AND Mu(H) + HX a
H(Mu) + F2

H(Mu) + Cl2

80.9◦b
86.7◦

83.2◦
87.7◦

β(H)
β(Mu)
a for

the abstraction reaction, Mu + HX →MuH + X.
b 1 degree = π/180 radians.

Another approach is to use the footnote.sty package (whichis part of Mark Wooding’s MDW Tools [8]) which allows
environments to be configured so as not to trap footnotes:\usepackage{footnote}\makesavenoteenv{tabular}

Note that is probably not a good idea to use footnotes infloating structures (like table) because the position of eachcan move relative to one another. To put the footnote at theend of a table instead of at the bottom of the page, justenclose tabular, etc., inside a minipage (no footnote packageneeded). A very good approach for handling footnotes withintables (including those that float) is to use Donald Arseneau’s
threeparttable package [14] which was used to generate Table
III (the code of which is an example in the threeparttable.styfile).
C. Double Column Floats
LATEX’s figure* and table* environments produce figures
and tables that span both columns. This capability can be usedwith the Steven Douglas Cochran’s subfigure package [15] toformat a set of related figures:\begin{figure*}\centerline{\subfigure[Case I]{\includegraphics[width=2.5in]{subfigcase1}\label{fig_first_case}}\hfil\subfigure[Case II]{\includegraphics[width=2.5in]{subfigcase2}\label{fig_second_case}}}\caption{Simulation results}\label{fig_sim}\end{figure*}

Note how labels can be tagged to each of the subfigures as wellas to the overall figure. \hfil is used as a subfigure separator
to achieve equal spacing around the graphics. More complex
implementations are possible. See the subfigure documentation
as well as the Using Imported Graphics in LATEX 2ε guide [11]for more details.
It is a limitation of the LATEX 2ε kernel that double column
floats cannot be placed at the bottom of pages. That is to say“\begin{figure*}[!b]” will not normally work as intended.
Authors that need this capability should obtain and load Sigitas
Tolušis’ stfloats package [16] which patches the LATEX 2εoutput routine to allow it to handle double column floats atthe bottom of pages. Please note that stfloats is a very invasive
package which may not work with versions of LATEX other than
the standard LATEX 2ε release and may cause problems withother packages that modify the output routines (such as thosethat balance columns, alter the placement of floating figures,etc.). IEEE authors are warned not to use packages that allow
material to be placed across the middle of the two text columns(such as cuted.sty, midfloat.sty, etc.) as IEEE does not do this.
Another LATEX 2ε limitation (patched with stfloats or not) isthat double column floats will not appear on the same page
where they are defined. So, the user will have to define suchthings prior to the page on which they are to (possibly) appear.
LATEX 2ε (patched with stfloats or not) does not attempt
to keep double and single column floats in sequence witheach other. This can be fixed by loading David Carlisle’s
fix2col package (already installed on most LATEX systems)[17]. However, fix2col should not be used with the stfloats
package as they both modify some of the same output routines
in different ways.
Finally, authors should also be aware that the LATEX 2ε kernel (patched with stfloats or not) has a long standing limitationin that it will not allow rubber space that spans both columns
to stretch or shrink as needed for each of the two main text
columns. Therefore, it is possible for double column floats tocause underfull vbox errors because the remaining text height
may not be equal to an integer number of normal size lines.
The problem can occur in main text columns (on pages withdouble column floats) that do not have vertical rubber spacing(such as that around section headings, equations, etc.) andresults in underfull vbox warnings coupled with paragraphsthat are “pulled apart” from each other. To correct this, users
can manually tweak the amount of space between the double
column structure and main text by inserting a command like\vspace*{-3pt}(adjusted as needed) within the double column structure. Incidentally, IEEEtran automatically compensates for this problem
when forming the paper title.
1) Double Column Equations: It is possible, but not pleasant, to use figure* to obtain double column equations. IEEE
rarely uses double column equations because they can waste
space, so this capability is easy to abuse. Authors who are
considering the use of a double column equation should verify
that there are a few examples of such in papers previously
published in the journal they plan to submit to.
There are complications. Although IEEE does not placeconstraints on the order of the double column equations
relative to the equations of the main text (that is to say a
set of double column equations can be at the top or bottomof a page in which they would normally appear in the middle
had they been regular equations), the double column equation
numbers must increase as one progresses down the page (i.e.,
double column equations at the bottom of a page must beof higher number than those at the top). Furthermore, double
column equations should appear on the same page where they
are referenced (on the page they would have appeared had
they been regular equations). Compounding the difficulty evenfurther is the fact that LATEX 2ε will not place double column
equations on the same page on which they are defined. Finally,
IEEE does not generally allow other figures or tables to comebetween the double column equations and the main text (which
are separated from each other by a rule). All of this means that

8

JOURNAL OF LATEX CLASS FILES, VOL. 1, NO. 11, NOVEMBER 2002

x = 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 + 21 + 23 + 25 + 27 + 29 + 31

(6)

y = 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18 + 20 + 22 + 24 + 26 + 28 + 30

(7)

the place where a double column equation must be defined has
to be “disconnected” from the place where it will eventually
be referred to in the text — and the user will have to manuallyintervene in the equation numbering system.
Therefore, users have to (1) define double column equations
on the page prior to the one that they are to appear; (2) resetthe equation counter when the double column equations aredefined so as not to disturb the regular equation numbers;(3) manually set the double column equation numbers and (4)increment the equation counter at the point the double column
equations are referenced in the text so that they are accounted
for in the numbering of the regular equations after that point.
To do all of this, it is convenient to have a “scratch pad”
counter to temporarily save equation numbers. This can bedone via a command such as\newcounter{mytempeqncnt}

in the preamble of the document. Now, the double column
equations are defined on the page prior to the one in which
they are to appear (and in this example supposed that they are
to be equation numbers six and seven):\begin{figure*}[!t]% ensure that we have normalsize text
\normalsize% Store the current equation number.
\setcounter{mytempeqncnt}{\value{equation}}% Set the equation number to one less than the one% desired for the first equation here.
% The value here will have to changed if equations% are added or removed prior to the place these% equations are referenced in the main text.
\setcounter{equation}{5}\begin{equation}\label{eqn_dbl_x}x = 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 + 21+ 23 + 25
+ 27 + 29 + 31
\end{equation}\begin{equation}\label{eqn_dbl_y}y = 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18 + 20+ 22 + 24
+ 26 + 28 + 30
\end{equation}% Restore the current equation number.
\setcounter{equation}{\value{mytempeqncnt}}% IEEE uses as a separator\hrulefill% The spacer can be tweaked to stop underfull vboxes.
\vspace*{4pt}\end{figure*}

The result of which is shown at the top of this page. This
technique allows the definition of the equations to be positioned arbitrarily as needed so that the (floating) equations
will appear where desired. The “[!t]” option forces LATEX to
do its best to place the equations at the top of the next page.
Had it been “[!b]” instead, then the stfloats package would
need to be loaded and the \vspace command, followed by
the \hrulefill command, would have to occur before theequations in the figure.

The double column equations can then been referenced in
the main text like:% The previous equation was number five.
% Account for the double column equations here.
\addtocounter{equation}{2}As can be seen in (\ref{eqn_dbl_x}) and(\ref{eqn_dbl_y}) at the top of the page ...

Thankfully, double column equations are rare.
X. L ISTS
The traditional
E itemize, enumerate and description(IED) list environments are ill-suited for producing the styleof lists used in IEEE publications. The main problem is thatthey do not provide the user a means for controlling theparameters of the resultant list. Furthermore, making globalchanges to the parameters of the underlying \list will result(often unexpectedly to a user) in the improper behavior ofother commands that depend on it, such as \quote. Finally,
LATEX’s \list considers the left margin of the list text to be
the reference point that determines how the list is positioned
relative to the left margin of the main text:
LAT X\labelwidth}|z\labelsep

{z

}|

{

Label

|

List Text{z}\leftmargin

This contrasts with IEEE lists which use the label box as
the reference point for the list structure. i.e., for a given
circumstance, the list labels will be indented by a certain
amount, the list text block will be indented from the label
boxes by a given amount and these spacings will determine
the position of the list text.
For these reasons, IEEEtran provides enhanced IED list
environments that make it much easier to produce IEEE stylelists. The underlying \list remains the same as in traditional
LATEX so as not to break code that depends upon it. IEEEtranuses a new length variable, \labelindent, so that users can
specify IED list structures directly in IEEE fashion:\labelwidth

z
Label

|

{z

}|

\labelsep

{z

}|

{
List Text}\labelindent

The IEEEtran IED lists ignore all “external” changes to the list
length parameters. Instead, IED lists are controlled exclusively
via two interfaces:1) “global” control via the \iedlistdecl command; and2) “local” control via an optional argument that can beprovided to \itemize, \enumerate, and \description.
For example, declaring\renewcommand{\iedlistdecl}{\settowidth{\labelwidth}{Hello}}SHELL: HOW TO USE THE IEEETRAN LATEX CLASS

in an IEEEtran document will set the default width of thelabel boxes in all later IED lists to be equal to the widthof “Hello”. Note: Because setting a \labelwidth is socommonly performed, IEEEtran provides a command: \setl
abelwidth{X} which is a shorter form of: \settowidth{\labelwidth}{X}.
The local control is used if the parameters are to apply only
to an individual IED list:\begin{itemize}[\setlabelwidth{$\gamma$}]Within an IED list, the local control is executed just after the
global control and therefore, the commands in the local control
can both augment and countermand those in the global control.
Please note that the code in the local and global controls are
executed in the same manner as normal LATEX code. Therefore,
the user should ensure that unwanted blank spaces do notappear in the controls. If a control definition is too long to
fit on one line, shield the end of lines with “%” to prevent
them from being interpreted as blanks. (Section III-B.1 hassome information on this topic.) Also, note that the LATEX
parser requires that braces be placed around commands with
optional arguments that are placed directly within the optional
arguments of other commands:\begin{itemize}[{\mycmd[1]{example}}]This IEEEtran IED implementation makes it easy to control
IED lists, even when they are deeply nested.
The default spacings the IED lists use are stored inlengths which begin with “IEEE”, i.e., \IEEEilabelinden
t. Changes to these “master” defaults are rarely needed andshould be done only at the beginning of the document, notin the IED list controls. These constants will now be briefly
explained.
\IEEEilabelindent: This length is the default amountthe itemized list label boxes are indented from the left margin.
IEEE seems to use at least two different values. For example,
in The Journal of Lightwave Technology and The Journal
on Selected Areas in Communications, they tend to use an
indention equal to \parindent, while for Transactions on
Communications they tend to indent itemized lists a little more
(1.3\parindent). The shorter length is stored as \IEEEila
belindentA and the longer as \IEEEilabelindentB. The
default is to use the shorter version. To use the longer version
do a\setlength{\IEEEilabelindent}{\IEEEilabelindentB}

at the beginning of the document.
\IEEEelabelindent: This length is the default amountthe enumerated list label boxes are indented from the left
margin. Normally, the same as \parindent.
\IEEEdlabelindent: Ditto for description list labels. Normally, the same as \parindent.
\IEEEiednormlabelsep: This length is the normal default spacing between the IED list label boxes and the list
text.
\IEEEiedmathlabelsep: For nomenclature description
lists (a list of math symbols and their explanations), IEEE
usually increases the separation between the terms and thedefinitions. This length is set to the longer than normal length.

9

To invoke its use, just issue the command \usemathlabels
ep in a list control.
\IEEEiedtopsep: This length is the extra vertical separation put above and below each IED list. IEEE usually puts
a little extra spacing around each list. However, this extra
spacing is barely noticeable.
\IEEElabelindentfactori through \IEEElabelinden
tfactorvi: These contain the factors by which the effective\labelindent is reduced as the list nesting depth increases.
IEEE normally decreases the amount of indention as the list
nesting level increases because there isn’t much room toindent with two column text. IEEEtran has an “automaticindention cut-back” feature that provides this behavior. The
actual amount the label boxes will be indented is \labelindent multiplied by the \IEEElabelindentfactorX
corresponding to the level of nesting depth (where “X” isthe nesting depth in roman numerals). This provides a meansby which the user can alter the effective \labelindentfor deeper levels. There may not be such a thing as correct“standard IEEE” values. What IEEE actually does may dependon the specific circumstances. The first list level almost always
has full indention. The second levels usually have only 75%of the normal indentation. Third level and greater nestings
are very rare, and probably don’t use any indentation. These
factors are not lengths, but rather constant macros like \baselinestretch so \renewcommand should be used if theyneed to be changed. The default values are\IEEElabelindentfactori
1.0\IEEElabelindentfactorii 0.75
\IEEElabelindentfactoriii 0.0\IEEElabelindentfactoriv 0.0\IEEElabelindentfactorv
0.0\IEEElabelindentfactorvi 0.0

The use of these factors in IED lists may be suspended byissuing the command \nolabelindentfactortrue in a list
control (which has the same effect as setting all the indent
factors to 1.0).
Normally, IEEEtran automatically calculates \leftmargin based upon the current values of \labelindent, \labelw
idth and \labelsep. To stop this auto-calculation so that amanually specified value of \leftmargin is used instead, justuse \nocalcleftmargintrue in a list control. This feature
should not be needed during the course of normal IEEE related
work.
IEEEtran provides a means to manually specify the justification within the IED list label boxes. The commands \iedlabeljustifyl, \iedlabeljustifyc and \iedlabel
justifyr can be used in a list control to justify the list
labels to the left, center, and right sides, respectively. Itemize
and enumerate lists automatically default to right justification,
while description defaults to left justification. The justificationcommands should not be needed during the course of normalIEEE related work.
In addition to modifying the behavior of itemize, enumer
ate and description, IEEEtran also provides the respective
aliases IEEEitemize, IEEEenumerate and IEEEdescript
ion, which provides a way for the user to access the IEEE
style list environments even in the event another package is10loaded that overrides the IED list environments. For specialized applications, the original LATEX IED list environments are
retained as LaTeXitemize, LaTeXenumerate and LaTeXdescription.
A. Itemize
The itemized lists will normally automatically calculate thewidth of whatever symbol the current list level is using sothat a user can just call \begin{itemize}...\end{itemize} without doing anything special. Furthermore, the autolabel-width feature will work properly even if \labelitemX
has been redefined (where “X” indicates “i,ii, .. iv”, whicheveris appropriate) before before the list begins. However, if any
item symbols are to be specified via \item[X] (this is rare
and may well be nonstandard as far as IEEE related work isconcerned), then the following form can be used:\begin{itemize}[\setlabelwidth{Z}]\item[X] blah\item[Y] blah.
.
\end{itemize}

where “Z” is the longest label in the list.
B. Enumerate
The important thing to note about enumerated lists is thatthe \labelwidth will default to the length of “9)” in thenormal size and style. Therefore, the width of the longest label
will have to be manually specified if any of the following
conditions are true:
1) a top level list has more than 9 items;2) a relevant \labelenumX or \theenumX has been redefined;
3) \item[X] has been used to manually specify labels;4) the labels are using a font that is not the normal sizeand style;5) the enumerated list is nested (i.e., not at the top level)
and is therefore not using Arabic digits as labels.
For example:\begin{enumerate}[\setlabelwidth{12)}]\item blah\item blah.
.
% 12 items total\end{enumerate}

JOURNAL OF LATEX CLASS FILES, VOL. 1, NO. 11, NOVEMBER 2002

Sometimes it can be difficult to ascertain from inspection
which of the labels is the longest. For such cases, a little
diagnostic code may be helpful to measure a length and thento display the result on the console:\newlength{\mydiaglen} % put in preamble.
.
\settowidth{\mydiaglen}{$\alpha\beta\gamma$}\showthe\mydiaglen

XI. T HEOREMS AND P ROOFS
Theorems and related structures such as axioms, corollaries
and lemmas, are handled in the traditional LATEX fashion. The
user must first declare the structure name via the\newtheorem{struct_type}{struct_title}[in_counter]

command where struct_type is the user chosen identifier
for the structure, struct_title is the heading that is used forthe structure and in_counter is an optional name of a counter
whose number will be displayed with the structure number
and whose update will reset the structure counter. Most IEEE
papers use sequential theorem numbering throughout the entire
work, so an in_counter is usually not specified. However,those papers that do use in_counter usually use “section”
such that the section number is the first part of each theorem
number. After the structure is defined it can be used via\begin{struct_type}[extra_title].
.
\end{struct_type}where extra_title is an optional name that is displayedwith the structure.
For example, the most common way to do theorems would
be to use
\newtheorem{theorem}{Theorem}

followed as needed by environments like\begin{theorem}[Einstein-Podolsky-Rosenberg]

Sometimes it is desirable that a structure share its counter
with another structure. This can be accomplished by using thealternate form of \newtheorem\newtheorem{struct_type}[num_like]{struct_title}

where num_like is the name of an existing structure.
A. Proofs

C. Description
Generally speaking, the longest label width will always haveto be specified for description lists. Furthermore, the author
may wish to use \IEEEmathlabelsep for \labelsep whenbuilding a math symbol list. For example:\begin{description}[\setlabelwidth{$\alpha\omega\pi\theta\mu$}\usemathlabelsep]\item[$\gamma\delta\beta$] Is the index of..
\item[$\alpha\omega\pi\theta\mu$] Gives the..
.
.
\end{description}

Proofs are easily handled by the predefined proof environment:\begin{proof}.
.
\end{proof}

The Q.E.D. symbol “ ” is automatically placed at the end ofeach proof. If needed, the symbol can be manually accessed
via the \QED command. Both the closed (default) “ ” andopen “ ” forms are provided as \QEDclosed and \QEDopen,
respectively. To change the default from closed to open (someSHELL: HOW TO USE THE IEEETRAN LATEX CLASS

journals and/or authors prefer the open form), just redefine\QED as desired:\renewcommand{\QED}{\QEDopen}

XII. E ND S ECTIONS
A. AppendicesThe \appendix command is used to start a single appendix.
An optional argument can be used to specify a title:\appendix[Proof of the Zonklar Equations]

After issuing \appendix, the \section command will bedisabled and any attempt to use \section will be ignored
and will cause a warning message to be generated. (The single
appendix marks the end of the enumerated sections and thesection counter is fixed at zero — one does not state “seeAppendix I” when there is only one appendix, instead “seethe Appendix” is used.) However, all lower \subsectioncommands and the \section* form will work as normal asthese may still be needed for things like acknowledgments.
\appendices is used when there is more than one appendix section. \section is then used to declare each appendix:\section{Proof of the First Zonklar Equation}

The mandatory argument to section can be left blank (\section{}) if no title is desired. It is important to remember todeclare a section before any additional subsections or labelsthat refer to section (or subsection, etc.) numbers. As with \appendix, the \section* command and the lower \subsec
tion commands will still work as usual.
There are two appendix numbering conventions used byIEEE. Capital letters (e.g., “Appendix A”) and Roman numerals (e.g., “Appendix I”). The former appears to be more
popular. However, since subsection numbering conventions
are preserved in the appendices, this creates rather awkward
subsection references like “A-A”. For this reason, IEEEtrandefaults to using Roman numerals when labeling appendices.
Appendix numbering can be changed to capital letters by
issuing the command\useRomanappendicesfalse

before \appendices is called.
Some authors prefer to have the appendix number to be partof equation numbers for equations that appear in an appendix.
This can be accomplished by redefining the equation numbersas\renewcommand{\theequation}{\thesection.\arabic{equation}}

before the first appendix equation. For a single appendix, theconstant “A” should be used in place of \thesection.
B. Acknowledgements
Acknowledgements and other unnumbered sections are created using the \section* command:\section*{Acknowledgment}\addcontentsline{toc}{section}{Acknowledgment}

11

The second, optional, command is needed to manually add
such sections to the table of contents (which is rarely used,
but some authors may do so with draft papers).
C. Bibliographies
Bibliographies are most easily (and correctly) generatedusing the IEEEtran BIBTEX package [18] which is easily
invoked via\bibliographystyle{IEEEtran}\bibliography{IEEEabrv,mybibfile}

See the IEEEtran BIBTEX package documentation for more
information.
When submitting the document source (.tex) file to external
parties (such as IEEE), it is strongly recommended that the
BIBTEX .bbl file be manually copied into the document (within
the traditional LATEX bibliography environment) so as not todepend on external files to generate the bibliography and toprevent the possibility of changes occurring therein.
D. Biographies
Biographies for journal articles are created using the biography environment which supports an optional argument for
the inclusion of a photo:\begin{biography}[{\includegraphics[width=1in,height=1.25in,clip,keepaspectratio]{./shell.eps}}]{Michael
Shell}.
.
\end{biography}

Note the extra set of braces that are required to prevent the
LATEX parser from becoming confused when commands with
optional arguments are used within an optional argument ofanother command. Alternatively, a LATEX macro (command)
could be defined to facilitate a shorthand notation for theauthor photos. If the optional argument is not used, space will
be reserved for a photo and the message “PLACE PHOTO
HERE” will be displayed in place of a photo.
IEEEtran is a tad overly cautious about preventing thebiography photo area from being broken across pages. If it
looks as though a biography should be able to be “squeezed”
at the end of a page, but instead it begins on a new page, try
inserting\vspace*{-2\baselineskip}

or so before the biography and see if it can fit.
IEEE’s algorithm for spacing around biographies can be atad complex because esthetics must be considered. IEEEtran
places \vfil above biographies. This allows the user to shove
biographies down or up as desired by placing the infinitely
more stretchable \vfill before or after the biographies.
The photo area is 1 in wide and 1.25 in long. IEEE recommends that author photo images should be of 220 dpi (dots perinch) resolution and in gray scale with 8 bits/sample.
If no photo is available, the \biographynophoto environment, which does not support an optional argument or reserve
space for a photo, can be used instead.

12

JOURNAL OF LATEX CLASS FILES, VOL. 1, NO. 11, NOVEMBER 2002

XIII. L AST PAGE C OLUMN E QUALIZATIONIEEE (coarsely) equalizes the lengths of the columns on
the last page. The balance is coarse in the sense that referenceor biography entries are not usually broken — so the column
lengths are not usually perfectly equal.
Balancing the last two columns is especially important for
camera ready work. It is recommended that authors use themanual approach by putting in \newpage at the appropriate
point or \enlargethispage{-X.Yin} somewhere at the topof the first column of the last page where “X.Yin” is theamount to effectively shorten the text height of the given page.
Sometimes such a command has to be located between
bibliography entries. This can be a problem because, although
the command can be placed within the .bbl file, it will getoverwritten the next time BIBTEX is run. For this situation,
IEEEtran offers a way to invoke commands just before a givenreference number via the \IEEEtriggeratref{} command.
For instance, issuing the command\IEEEtriggeratref{10}before the bibliography will insert a page break just before
reference number ten. The command that is executed defaults
to \newpage. However, this can be changed via the \IEEEtriggercmd command:\IEEEtriggercmd{\enlargethispage{-5.35in}}Note that manually set break points or page sizes will have tobe readjusted if the document content ever changes.
There are LATEX packages, such as balance.sty [19] andflushend.sty [20], that are designed to automatically balance
the columns on the last page. Flushend does not require theplacement of any special command in the first column of thelast page, balance.sty may. However, the use of these packages
is not recommended because they are known to be less thanperfectly reliable in their operation. The author of balance.sty
does not guarantee that it will work with every possible typeof page, especially pages with figures. Under certain circumstances, flushend.sty will cause a spacing anomaly between
two lines within a reference in the second column of the last
page (becomes larger than the space between references). This
problem seems to result because the bibliography in IEEEtranis a list with zero space between the list items which are infootnotesize. The problem can also occur under article.cls forthe same type of list. It may be possible to manually correct
the flushend anomaly by tweaking the spacer at the column
break via a flushend command such as “\atColsBreak{\vskip-2pt}”, but having to do so partially defeats the purposeof using the package in the first place. If using flushend.sty orbalance.sty, be sure to check the document carefully for any
spacing problems — especially on the last page.
A PPENDIX II NSTALLING IEEE TRANLATEX .cls files can be accessed system-wide when they areplaced in the<texmf>/tex/latex

directory, where <texmf> is the root directory of the user’s
TEX installation. It is recommended that the user create asubdirectory<texmf>/tex/latex/IEEE

for all IEEE related LATEX class and package files. On some
LATEX systems, the directory look-up tables will need to berefreshed after making additions or deletions to the systemfiles. For teTEX and fpTEX systems this is accomplished via
executingtexhashas root. MiKTEX users can run
initexmf -u

to accomplish the same thing.
Users not willing or able to install the files system-wide
can make the copies local, but will then have to provide thepath (full or relative) as well as the filename when referringto them in LATEX.
A PPENDIX IIP OST S CRIPT /PDF O UTPUT
Unfortunately, many LATEX systems are not properly configured to produce quality PostScript and/or PDF output. This iseven more of a problem with IEEE related work because thefont combination IEEE uses is known to cause problems withsome LATEX setups — especially those that were installed prior
to mid-2002. This has been a chronic and very aggravating
issue for many organizations that accept work created using
LATEX.
To assist IEEE authors in detecting and correcting problems
with LATEX PostScript/PDF generation, the “Testflow” diagnostic suite was developed [21]. Authors are strongly encouraged
to take the time to go through the testflow diagnostic andidentify and correct potential problems before their LATEX
systems have to be relied on for production work. Papers withproblems such as incorrect margins, font types, PDF format
errors and/or improper font embedding can incur delays during
the manuscript acceptance process.
A PPENDIX III
OTHER U SEFUL E XTERNAL PACKAGES
A. The url.sty Package
Papers that contain URLs, email address, etc., can likely
benefit from the use of the url.sty LATEX package [22] which
provides for more intelligent line breaking within such structures.
B. The IEEEtrantools Package
Some of the unique commands provided by the IEEEtran
LATEX class may be of use in non-IEEE related work using
other class files (e.g., dissertations, technical reports, etc.). The
IEEEtrantools.sty package [23] provides several popular IEEEtran commands including \PARstart, the IEEE style IEDlist environments, and the IEEEeqnarray family of commands.
The IEEEtrantools package is not needed under, and should
not be loaded with, the IEEEtran class. See the IEEEtrantools
documentation for more details.

SHELL: HOW TO USE THE IEEETRAN LATEX CLASSA PPENDIX IV
C OMMON U SER M ISTAKES
Most user mistakes with IEEEtran involve doing too muchrather than too little. Older class files may have required hacks
in order to get the formatting closer to that of IEEE. These
tweaks are no longer needed. Users should carefully checkall the loaded packages to ensure that they are still useful
under the latest version of IEEEtran. Don’t load packages justbecause “this is the way it always has been done.” The sameis true for manually adjusted spacing, margins, paper sizes,
etc.
Another common category of error is to do things thatcompromise the portability of the LATEX code. If the .tex sourcecode will ever have to be shared with another party (IEEE, etc.)
it is important to code in traditional LATEX fashion and not toutilize system dependent features, interfaces, graphics formats,drivers or fonts — and pdfLATEX users should ensure that their.tex code will also compile successfully without modification
on traditional LATEX/DVIPS systems.
Below are a few of the more commonly encountered mistakes to avoid.
Altering the default fonts: Authors should allow IEEEtran
to manage the fonts. Do not attempt to use packages that
override the default fonts such as pslatex, mathptm, etc.
Likewise, authors should not attempt to alter the default fontencoding (fontenc.sty) or input encoding (inputenc.sty).
Altering the default spacings, section heading styles,
margins or column style: Authors should not attempt tomanually alter the margins, paper size (except as provided
in IEEEtran class options) or use packages that do so (geometry.sty, etc.) There should be no need to add spacing aroundfigures, equations, etc. (Except possibly for double column
floats as described in Section IX-C.)
Using incorrect graphics file formats: LATEX has always
favored the use of Encapsulated PostScript (EPS) for graphics— and for good reason. EPS supports both vector (thatis, containing objects such as lines, circles, etc., that aremathematically described) and bitmap (that is containing only
samples in the form of pixels) images. The former should
always be used for drawings, graphs, charts, etc., while thelatter usually has to be employed with photos (because theircontents usually cannot be easily described mathematically).
The drawing and graphing tools used by the author should becapable of outputing directly8 in vector (EPS) format. Vector
EPS images can be scaled, rotated and magnified without
undergoing degradation such as pixelization or becoming grayor “jaggedy.” For photos, IEEE recommends the use of EPS(which is easy to directly import into LATEX in a portablemanner) or TIFF. The use of other graphic formats such as
BMP, EMF, etc., is currently unacceptable for IEEE journals.
IEEE conferences typically support more graphics formats
than IEEE journals. For example, the use of PDF graphics(with pdfLATEX) should be acceptable for conference papers.
Using older graphics packages: Authors should not use
8 Once an image in EPS vector form is converted to a bitmap form (GIF,
TIFF, JPEG, etc.) it will almost always be irretrievably locked into bitmap
form even if it is later converted back into EPS.

13

anything other than the graphics and/or graphicx (preferred)
package for figures. Older interfaces such as psfig, epsf, etc.,
have been obsolete for many years.
Specifying graphics drivers: When loading the graphics
or graphicx package, authors should not specify an optionalgraphics driver, e.g.,\usepackage[pctex32]{graphicx}

because such code will not work properly on other systems thatuse a different graphics driver. If the default driver (which isloaded when none is specified) is incorrect for a LATEX system,
it is best to alter the <texmf>/tex/latex/config/graphi
cs.cfg file than to have to manually specify a graphics driverin every .tex file. It should be acceptable to load the pdftex
driver provided that the user’s .tex code first tests for the useof pdflatex. The bare example files contain code that illustrates
how to properly do this.
Failing to properly divide long equations: It is the author’s
responsibility to ensure that all equations fit within the width oftheir columns. Admittedly, breaking an equation is not always
easy to do and two column formatting places serious constraints on allowed equation width. However, only the author
can divide his/her equation without unintentionally altering its
meaning or affecting readability. Using subfunctions is a valid
way to reduce to width of an equation, but altering the mathfont size is not.
Manually formatting references: Not only is this error
prone, but requires a lot of work as well. It is better to use
the IEEEtran BIBTEX style [18].
A PPENDIX V
K NOWN I SSUES
The small caps font used in the free LATEX systems haveabout 80% the height of normal sized letters. However, thesmall caps font IEEE uses in the journals is slightly smallerwith a ratio of around 75%. So, the widths of the section
headings produced under the free LATEX systems will beslightly wider than that used in actual journals. The small caps
font used in many commercial LATEX systems (such as thosefrom YandY) has a ratio of about 65%. So, those systems willproduce section headings that are narrower than those in IEEE
publications. Such variations should not be cause for concern.
hyperref.sty versions prior to 6.72u will interfere with theoptional argument to \appendix. It is difficult to ensurethat LATEX packages are fully compatible with hyperref.sty.
Therefore, the use of the hyperref package is not recommended
for documents that are to be submitted to IEEE. In particular,
it is known that current versions of cite.sty and hyperref.sty do
not work together. IEEEtran.cls mediates these two packages
in a way that allows cite.sty to work as normal, but without
the citation numbers being hyperlinked by hyperref.sty. See
the comments in the bare template files for more details.
The amsthm.sty package will cause a name clash error as
it will try to define a proof environment which is alreadyprovided by IEEEtran.cls. It is generally not a good idea toload packages that attempt to provide replacements for any of
the custom commands provided by IEEEtran.cls.

14

JOURNAL OF LATEX CLASS FILES, VOL. 1, NO. 11, NOVEMBER 2002

TABLE IVA PPENDIX VI
T HE IEEE EQNARRAY C OMMANDS(Optional — for advanced users)

Virtually all LAT X alignment commands such as \eqnarrEay, \array and \tabular are based on the TEX command\halign. LATEX’s goal of simplifying the use of \halign isnoble. However, in hiding much of the lower level interface,a fair degree of flexibility is lost. This has resulted in the development of several packages such as amsmath [7], array.sty[13], and the MDW tools [8], each of which provides much
more powerful alignment structures.
IEEEtran also provides its own unique set of alignment
tools which are known as the IEEEeqnarray family. The
design philosophy of the IEEEeqnarray family is to provide
a LATEX alignment interface that is based more closely on theunderlying \halign, but to couple this with high level column definition management and automated preamble building
mechanisms (which are tedious to do in TEX). As a result,the IEEEeqnarray family of commands are flexible enoughto be almost universal replacements for all the other LATEX
commands for producing multiline equations and aligned box
structures such as matrices and tables of text and/or mathematics. Because the user is shielded less from the \halignunderpinnings, the rules of operation are more involved. So,
the IEEEeqnarray commands are aimed primarily toward themore advanced LATEX users.
The use of the IEEEeqnarray family of tools described inthis section is totally optional. The IEEEeqnarray code is selfcontained and does not depend on other alignment packages— which can be used along side, or in place of, it. The
IEEEtrantools.sty package (See Appendix III-B) is available
for those who wish to use the IEEEeqnarray family outside ofIEEEtran.cls.
A. IEEEeqnarray
The IEEEeqnarray environment is for multiline equations
that occupy the entire column. It is used in much the same
way as \eqnarray, but with two additional arguments, oneof which is mandatory and the other is optional:\begin{IEEEeqnarray}[decl]{cols}.
\end{IEEEeqnarray}

The optional argument is for commands that are to be executed
within the environment, but before the alignment actually begins. This is just like the local control of the IEEEtran IED list
environments. There is also a global control, \IEEEeqnarraydecl, which is executed just prior to the local control. By
default, \IEEEeqnarraydecl is defined to be \relax. As
mentioned in Section X, users should be careful not to allow
unwanted spaces to occur in these controls because suchthings will appear just before the IEEEeqnarray structure.
Furthermore, remember that, to prevent the LATEX parser frombecoming confused, the contents of an optional argument must
be enclosed in braces if the argument contains commands with
optional arguments.

IEEE EQNARRAY P REDEFINED C OLUMN T YPES
I.D.

Description

I.D.

Description

l
c
r
L
C
R
s
t
u

left mathcentered mathright mathleft math with ords
centered math with ords
right math with ords
left text
centered text
right text

v
vv
V
VV
h
H
x
X

vertical rule
two vertical rules
double vertical rule
two double vertical rules
horizontal rule
double horizontal rule
empty
empty mathNote: S, T, U, p, and P are likely to be used in future versions.

TABLE VIEEE EQNARRAY P REDEFINED C OLUMN S EPARATION (G LUE ) T YPES
I.D.

Width*

I.D.

Width

!
,
:
;
’
"

−1/6 em

.
/
?
*
+
-

0.5\arraycolsep

1/6 em2/9 em
5/18 em
1 em
2 em

1.0\arraycolsep
2.0\arraycolsep

0pt plus 1fil
1000pt minus 1000pt
0pt* All em values are referenced to the math font.

1 em = \quad,

2 em = \qquad

The mandatory argument cols contains the column andinter-column separator spacing (“inter-column tabskip glue”
in TEXspeak) type specifiers. Column types are identified byletters. Several predefined column types are available as shownin Table IV. There are two kinds of glue types. Predefined glue
types are indicated by various punctuation marks as shown in
Table V. User defined glue types are indicated by numbers.
The rules for placing these specifiers are as follows: (1) notwo glue specifiers can appear next to each other — they are
not additive and must be separated from each other by at least
one column specifier; (2) zero inter-column spacing will beassumed between back-to-back column specifiers; (3) becauseof rule one, back-to-back numerals will be considered as beinga single glue specified by the numerical value represented by
all the digits; (4) a multiletter column specifier can be accessedby enclosing the letters within braces (otherwise it would beinterpreted as being several single letter column specifiers).
Because of rule three, braces are not needed around multidigit
glue specifiers; (5) there must be at least one column specifier,but there is no fixed upper limit of how many columns can besupported; and (6) for \IEEEeqnarray, “+” centering glue
will be assumed at each end of the cols specification if
no column glue is specified there. This results in a centeredstructure like \eqnarray (the 1000pt minus 1000pt glue oneach side “compresses” as needed from each side of the main
text column to center that which is between). Also, \IEEEeqnarray automatically adds a hidden column for equation
numbers to the right of the last specified column. Currently,
there is no support for equation numbers on the left side.9
9 This is not to say that its impossible with the existing capability, just ugly.

SHELL: HOW TO USE THE IEEETRAN LATEX CLASS

B. Defining Column Types
New column types are defined with the\IEEEeqnarraydefcol{col_id}{predef}{postdef}

command. The col_id argument contains the name of thecolumn specifier which should consist only of one or moreletters. A given column specifier, even the predefined ones, canbe redefined at will without warning or error.10 The predef
argument contains the commands that will be inserted before
each cell in the column. The postdef argument contains thecommands that will be inserted after each cell in the column.
For example,\IEEEeqnarraydefcol{g}{\hfil$\clubsuit$}{$\diamondsu
it$\hfil}Will define a “g” text column which will place club anddiamond suit symbols on either side of a cell’s contents andcenter the respective structure within the cell. e.g.,♣Hello♦Using \hfil to control cell alignment allows the user
to override the column alignment on a cell-by-cell basis byplacing the infinitely more stretchable \hfill on one or bothsides of a cell’s contents. \hfill can even be placed between
items in a cell to force them apart and against the “cell walls.”
The IEEEeqnarray predefined columns are designed to allow
user overrides via \hfill whenever possible (even for themath mode cells).
Please note that TEX will not allow unmatched braces within
the arguments of commands. If braces are needed, such as forthe argument of a command, they will have to be provided
within the cells themselves. For example,\IEEEeqnarraydefcol{myp}{\parbox[c]{0.5in}}{}\begin{IEEEeqnarraybox}{{myp}c}{first\\second}&\alpha\\&\beta%\end{IEEEeqnarraybox}

defines a column type named “myp” that will place text within
a 0.5 inch wide parbox which is centered on the cell’s baseline.
Note that because the column type name consists of more than
one letter, it has to be enclosed within an extra set of bracesin the column specifications or else it would be interpreted as
three adjacent columns “m,” “y,” and “p.” Also, the contentsof the cell must be enclosed within braces so that (1) the \parbox command sees the entire contents as its argument; and (2)the newline within the parbox will not be interpreted as being
the end of the alignment row. Be aware that it can happen thata column is given an empty cell, such as in the second row inthe example, or when entering blank separator rows. When thishappens, a \relax will appear in the column which will beacquired as the command’s argument. Therefore, commands
in column definitions that acquire arguments from the cells
should not choke if fed \relax.
For reference, the definitions of the predefined column types
are shown here:% math\IEEEeqnarraydefcol{l}{$\IEEEeqnarraymathstyle}{$\hfil}
10 Thus allowing new predefined column types to be added without breaking
existing code.

15\IEEEeqnarraydefcol{c}{\hfil$\IEEEeqnarraymathstyle}{$\hfil}\IEEEeqnarraydefcol{r}{\hfil$\IEEEeqnarraymathstyle}{$}\IEEEeqnarraydefcol{L}{$\IEEEeqnarraymathstyle{}}{{}$\hfil}\IEEEeqnarraydefcol{C}{\hfil$\IEEEeqnarraymathstyle{}}{{}$\hfil}\IEEEeqnarraydefcol{R}{\hfil$\IEEEeqnarraymathstyle{}}{{}$}% text\IEEEeqnarraydefcol{s}{\IEEEeqnarraytextstyle}{\hfil}\IEEEeqnarraydefcol{t}{\hfil\IEEEeqnarraytextstyle}{\hfil}\IEEEeqnarraydefcol{u}{\hfil\IEEEeqnarraytextstyle}{}% vertical rules\IEEEeqnarraydefcol{v}{}{\vrule width\arrayrulewidth}\IEEEeqnarraydefcol{vv}{\vrule width\arrayrulewidth\hfil}{\hfil\vrule width\arrayrulewidth}\IEEEeqnarraydefcol{V}{}{\vrule width\arrayrulewidth\hskip\doublerulesep\vrule width\arrayrulewidth}\IEEEeqnarraydefcol{VV}{\vrule width\arrayrulewidth\hskip\doublerulesep\vrule width\arrayrulewidth\hfil}%{\hfil\vrule width\arrayrulewidth\hskip\doublerulesep\vrule
width\arrayrulewidth}% horizontal rules\IEEEeqnarraydefcol{h}{}{\leaders\hrule height\arrayrulewidt
h\hfil}\IEEEeqnarraydefcol{H}{}{\leaders\vbox{\hrule width\arrayrul
ewidth\vskip\doublerulesep\hrule width\arrayrulewidth}\hfil}% plain\IEEEeqnarraydefcol{x}{}{}\IEEEeqnarraydefcol{X}{$}{$}

Note the inclusion of the commands \IEEEeqnarraymat
hstyle and \IEEEeqnarraytextstyle in the math andtext columns, respectively. These commands allow the user
to control the style of all of the math and text columns.
However, because the changes apply to all the columns, theuser will have to define new column types if different styles
are needed in the same alignment (or different styles can be
manually specified in each cell). The default definitions forthese commands are\newcommand{\IEEEeqnarraymathstyle}{\displaystyle}\newcommand{\IEEEeqnarraytextstyle}{\relax}

which allows the text columns to be in whatever style was ineffect when the alignment was started and the default mathstyle will be in display style, but can be easily changed asneeded. e.g.,\begin{IEEEeqnarray}[\renewcommand{\IEEEeqnarraymathstyle}{\scriptstyle}]{rCl}will result in script style math columns.
The columns relating to vertical and horizontal lines will
be discussed in Section VI-K as they are typically used only
when producing tables.
The “x” and “X” columns are basic empty text and mathmode columns without any formatting or style controls.
C. Defining Glue Types
New column separation glue types are defined with the\IEEEeqnarraydefcolsep{colsep_id}{def}command. The colsep_id argument contains the number ofthe column separation glue specifier which should consist onlyof numerals. Different glue type names must have different
numerical values. (Don’t get too cute — “007” is identicalto “7”.) User defined column glue specifiers can be redefined
at will without warning or error. The def argument contains
the width of the given glue type. Widths may be specified asabsolute values or reference length commands:

16

JOURNAL OF LATEX CLASS FILES, VOL. 1, NO. 11, NOVEMBER 2002

\IEEEeqnarraydefcolsep{9}{10pt}\IEEEeqnarraydefcolsep{11}{2\tabcolsep}

mber or \IEEEyesnumber as needed in the last column.11 \I
EEEeqnarray also provides a \IEEEyessubnumber which

The glue type widths are not evaluated when defined, but areevaluated each time they are actually referenced as IEEEeqnarray column specifiers. Thus, for the second definition in
the example above, if \tabcolsep were to be revised after
the glue type was defined, the revised value would be what is
used.
Rubber lengths are allowed too. The fact that the centering
glue “+” is a known value can be exploited to achieve someinteresting effects. For example,

can be used to enable a subequation number for the given
line:\IEEEeqnarraydefcolsep{17}{200pt minus 200pt}

will produce a column separation glue that is always 1/5 of
the width of the distance from the equation sides to the endsof the main text columns. And, of course, “+” can be used asneeded to produce groups of equally spaced equations as inamsmath’s \align:\begin{IEEEeqnarray}{Rl+Rl+Rl}

D. A Simple Example of Use
The example in Section VIII can be implemented using\IEEEeqnarray via\begin{IEEEeqnarray}{rCl}
Z&=&x_1 + x_2 + x_3 + x_4 + x_5 + x_6\IEEEnonumber\\&&+\:a + b%\end{IEEEeqnarray}

As shown in Table IV the “C” column type is a centered mathmode column with empty ords (“{}”) on either side. So, there
is no need to place empty ords around the equal sign. As with\eqnarray, the & separate the column cells and are where
the inter-column separation glue will appear (when nonzero).
Note the presence of the % at the end of the second row.
TEX does not ignore spaces that occur before commands or& column delimiters, but does ignore those that occur after.
Most LATEX alignment implementations shield the user fromthis behavior by removing all spacing previous to &, \\ and\end. The IEEEeqnarray family does not do this! So, it isimportant to prevent spaces (including implied ones at the endof lines) from occurring before such commands unless they arewanted. Suspect this problem if there is an unexplained offset
within a column. In the given example, unwanted spacing is
not an issue because end spacing is ignored in math mode
anyway. However, it would be an issue if the columns used
text mode instead.
Alternatively, one could use a two column form:\begin{IEEEeqnarray}{Rl}
Z=&x_1 + x_2 + x_3 + x_4 + x_5 + x_6\IEEEnonumber\\&+\:a + b%\end{IEEEeqnarray}

E. Equation Numbering
Like \eqnarray, \IEEEeqnarray, has a “star form,” \IE
EEeqnarray*, which does not place equation numbers at theend of each row by default. The default behavior of individualrows can be overridden by placing the commands \IEEEnonu&+\:a + b\IEEEyessubnumber\label{myfirstsubeqn}\\

Note that labels for subequations must be placed after the\IEEEyessubnumber command because, prior to that point,

the label will reference the equation number that would havebeen used if there had not been a request for a subnumber. To
support this feature, IEEEtran defines its own IEEEsubequation counter (reset with changes to equation) and \theI
EEEsubequation command.12 The first line without an \IE
EEyessubnumber will revert back to conventional equation
numbering. Currently, there is no support for subequation
numbering to be the default for all the lines. So, users will
have to call \IEEEyessubnumber every time a subequation
number is needed.
Please be aware that \IEEEeqnarray, like \eqnarray,
will, if the equation is long enough, overwrite the equation
number without warning!13 For cases when this happens, users
can insert a \IEEEeqnarraynumspace command at the endof the line (after any \IEEEyessubnumber if used) which
will insert a space equal in width to the displayed equation
number:· · · + x_z \IEEEyessubnumber\IEEEeqnarraynumspace\\

As a result, the entire multiline equation will be slightly shiftedto the left. IEEE often does the same thing in its journals whenconfronted by this situation. If an overfull hbox results, theoffending equation line will have to be further divided.
F. Extra Vertical Spacing and Page Breaks
Like \eqnarray, \IEEEeqnarray’s \\ command supports
a star form which inhibits page breaks at the given line as wellas an optional extra vertical spacing argument:&+\:a + b\\*[5pt]

Users are reminded from Section VIII that amsmath will
configure LATEX to disallow page breaks within multiline equations — including those made by \IEEEeqnarray because it
also honors the value of \interdisplaylinepenalty.
Also like \eqnarray, \IEEEeqnarray normally placesa small amount of extra spacing (as specified by the lengthcommand \jot) between lines to “open up” equations as wellas to prevent large symbols from coming to close to the lines
above them.
G. IEEEeqnarraybox\IEEEeqnarray is not suitable for producing structures
such as matrices and tables because it must have exclusive
11 The aliases \nonumber and \yesnumber are also provided. However,their use is not recommended because some packages (such as MDW tools)
redefine them in an IEEEeqnarray incompatible way.
12 What is actually displayed is the \theIEEEsubequationdis command.
13 This behavior is extremely difficult to avoid if the equation line is toremain centered irrespective of the width of the equation number — withouteven considering the subjective question of how close is too close for any
given case!

SHELL: HOW TO USE THE IEEETRAN LATEX CLASS

access to the main text column and cannot be nested within
other structures. For these applications, the \IEEEeqnarraybox command is provided. \IEEEeqnarraybox differs from\IEEEeqnarray in the following ways:
1) the entire contents are wrapped within a box and therefore, can be nested within other display or alignment
structures (such as \equation, \IEEEeqnarray oreven another \IEEEeqnarraybox). Note that, like allbox structures, page breaks are not allowed between therows of an \IEEEeqnarraybox;
2) the default glue at the outer ends of the first and lastcolumns is 0 pt (“-”), not “+” centering glue as with \I
EEEeqnarray;3) no automatic (hidden) equation number column is provided;4) the star form “\IEEEeqnarraybox*” turns off the extra\jot vertical spacing after each row;
5) \IEEEeqnarrayboxdecl is the global control.
Two subforms are provided: \IEEEeqnarrayboxm which
is for use within math modes and is analogous to \array;and \IEEEeqnarrayboxt which is for use within text modes
and is analogous to \tabular. If called via \IEEEeqnarra
ybox the current math/text mode will be auto-detected andthe proper subform will automatically be selected. Therefore,\IEEEeqnarraybox can replace \array as well as \tabular.
The syntax for \IEEEeqnarraybox is similar to \IEEEeq
narray, but with two additional optional arguments:\begin{IEEEeqnarraybox}[decl][pos][width]{cols}.
\end{IEEEeqnarraybox}

The pos argument can be one of t, c, or b to control where thebox will be vertically aligned relative to the current baseline:
t at the top row; c at the center;14 b at the bottom row. The
default is b.
The width argument specifies the width the box. Warning:
if a width is specified, there must be one or more rubber
lengths in the inter-column glue specifiers (such as that of “*”or “+”) so that the box can be sized as needed. If there is nosuch glue, or the glue provided cannot stretch/shrink enoughas needed, the box cannot be sized to width and an underfull
or overfull hbox error will result. If no width argument isprovided, the box will be set to its natural width (and the useof rubber inter-column glue will not be required).
\IEEEeqnarraybox uses the same column and glue typespecifiers/definitions as \IEEEeqnarray.
H. Line Spacing in LATEX
Before discussing some of the more advanced aspects ofvertical spacing control in the IEEEeqnarray family, it is important to review the details of LATEX’s line spacing algorithm.
Normally, baselines are separated by the amount given by thelength command \baselineskip. With each change in fontsize, \baselineskip is reset to the default value for that font
14 Centering is actually done along the “math axis”, not exactly on the text
baseline (but quite close to it). Most LATEX users are not aware of this minor
distinction.

17

size (multiplied by \baselinestretch). Then the value of\baselineskip is saved to the length variable \normalbas
elineskip (so that the normal value can be later referenced
even if \baselineskip is set to another value by the user).
However, if the top of a line ever gets closer than \lineski
plimit to the bottom of the line above it, the use of \basel
ineskip will be suspended and \lineskip spacing will beplaced between the two lines.15
This system works well for text. However, for mathematics,
whose symbols have a much higher dynamic range of heights
and depths, it is usually better to go ahead and always add anextra fixed amount of space (\jot) as mentioned in Appendix
VI-F.
When the IEEEeqnarray family is loaded, two new lengthcommands are defined: \normaljot and \normalsizebas
elineskip which store the nominal values of \jot16 andthe \baselineskip of the normalsize font, respectively, sothat they can be always be referred to even if other values are
currently being used.
At the start of \IEEEeqnarray/box, but before the local
or global controls, the following initialization takes place:\lineskip=0pt\lineskiplimit=0pt\baselineskip=\normalbaselineskip\jot=\normaljot

Thus, \baselineskip is set to the normal value for thecurrent font, \jot is restored to its nominal value and the\lineskiplimit system is disabled.17
This system is designed to better facilitate nested IEEEeqnarraybox structures as well as to help prevent the user fromencountering seemingly uncontrollable spacing behavior (e.g.,“How do I get rid of that unwanted space?!”).
I. The IEEEeqnarray Strut System
When creating tables, especially tables with vertical rules,
vertical space between the rows of the table is not generally
desirable because such space will suspend the column celldefinitions and “cut across” any vertical rules that may bepresent. Yet, there must be a way to keep rows adequately
spaced apart. To solve this problem, the IEEEeqnarray/box
commands provide an integrated system to manage struts18
contained in a hidden column on the right end of each
IEEEeqnarray/box structure.
The struts in each row will be set to a default strut heightand depth. Normally, the default strut height and depth are
initialized to zero, so the struts will effectively not be present.
The user can set the default strut values via the\IEEEeqnarraystrutsize{height}{depth}[decl]

command which can be placed in a local or global control. The
optional argument is for commands which will be executed
15 Within IEEEtran.cls, \lineskiplimit and \lineskip are zero —if things get too close it is the author’s responsibility to correct the problem
without having IEEEtran.cls second guessing the author’s intent.
16 Within IEEEtran.cls, the nominal value of \jot is 25% of the baselineskip for the normalsize font.
17 As long as rows cannot be of negative height.
18 “Struts” are vertical rules of zero width, but of finite height.

18

prior to the evaluation of the height and depth arguments.
Thus,\IEEEeqnarraystrutsize{0.5\baselineskip}{}[\large]

will set the default strut height to half the baselineskip used by
the large font size, even if the current baselineskip (and/or fontsize) is different. The commands which are executed within theoptional argument are contained within their own environmentso as not to have any effects outside of the \IEEEeqnarra
ystrutsize command. For mimicking the action of \baselineskip, the typically recommended height and depth of
struts is 70% and 30%, respectively, of \normalbaselines
kip19 . \IEEEeqnarraystrutsize will assume these values
if its height and/or depth arguments are left blank. e.g., in theprevious example, the strut depth will be set to 30% of \normalbaselineskip for the large font size.
There is also a\IEEEeqnarraystrutsizeadd{height}{depth}[decl]

command which will add to the current default strut values
and can be used much like the \extrarowheight parameterof the array.sty package. Empty arguments are assumed to be
0 pt.
\IEEEeqnarraystrutsize and \IEEEeqnarraystruts
izeadd can also be used at the end of the last column to alter
the strut size used for a particular row (the default strut valuesof the other rows will not be affected).
There is also a\IEEEstrut[height][depth][decl]

which produces a strut. It can be used whenever a “manual”
strut is needed — even outside the \IEEEeqnarray/box
environments. If a height or depth argument is not provided(or empty) then these will be assumed in the same way as\IEEEeqnarraystrutsize does.
For diagnostic purposes (in order to see if any row objects
exceed the height of the struts), the command \IEEEvisibl
estrutstrue can be placed with an \IEEEeqnarray/box
or \IEEEstrut control to make the struts visible.
When using \IEEEeqnarraybox to produce tables that
contain vertical lines, it is usually desirable to shutdown the\baselineskip system and switch over to pure strut spacing.
The following command sequence, placed within a local or
global control, will serve this purpose:\IEEEeqnarraystrutsize{0.7\normalbaselineskip}{0.3\normalbaselineskip}[\relax]\setlength{\baselineskip}{0pt}%\setlength{\lineskip}{0pt}%\setlength{\lineskiplimit}{0pt}%\setlength{\jot}{0pt}%

Note the use of “%” to prevent the ends of the lines that end
in braces from being interpreted as unwanted spaces. Becauseof the frequent need to call this sequence, the IEEEeqnarrayfamily provides the \IEEEeqnarraystrutmode command
which does the same thing.
19 Note that this not the normalsize baselineskip, but the normal baselineskip
for the current font.

JOURNAL OF LATEX CLASS FILES, VOL. 1, NO. 11, NOVEMBER 2002

J. Overriding Column Types
Within a row, one or more column types can be overriddenby placing the command\IEEEmulticol{num_cols}{col_type}{text}

as the very first command in a cell. This command is theIEEEeqnarray equivalent of \multicolumn. The first argument is the number of columns to override (cutting throughany inter-column glues as needed). The second argument is thecolumn type specifier to use. The third argument contains thecell text. The third argument will have to be enclosed within
an extra set of braces if the column type is to acquire it as
an argument — as was done with the “myp” parbox column
type in the example earlier in this Appendix (VI-B).
There is also the \IEEEeqnarrayomit command which,when used as the very first command in a cell, will suspend theuse of the normal column type for that cell. This is somewhat
like a quicker version of \IEEEeqnarraymulticol{1}{x}{}.
Users are cautioned not to use commands like these (e.g.,\multicolumn) that are designed for other alignment environments.20
K. Predefined Column Types for Rules
Several of the predefined column types produce vertical or
horizontal lines. Note that, in the IEEEeqnarray family, rules
are declared and treated as normal column types — they are
not hidden. Although this approach may increase the numberof columns the user has to keep track of, especially whencreating tables, it does offer a great deal of flexibility byallowing the user to override, or otherwise manipulate, any
column type (including those that produce rules) at will.
All of the predefined rule column types use the \arrayru
lewidth length to determine the line thickness and \doubl
erulesep for the spacing of double rules.
The “v” column type produces a vertical rule, “vv” produces
two back-to-back vertical rules which will appear as one ruleof twice the normal thickness. “V” produces a double verticalrule with \doublerulesep spacing between its two lines.
“VV” produces two back-to-back double vertical rules which
will appear to be three vertical rules, the middle one of whichbeing twice as thick as the other two. It is possible to “spreadapart” the “vv” and “VV” types by placing a spacer within
their columns — thus they can be used to generate two
single, or double, vertical rules whose separation distance isprogrammable.
The “h” and “H” types produce single and double horizontal
rules, respectively. Horizontal rule types are not normally usedin the column specifications, but rather with the \IEEEeqna
rraymulticol command in order to draw a horizontal rule
across one or more column(s).
Please be aware that the line commands of other alignment
environments may not work properly within the IEEEeqnarray
20 Those familiar with T X may be interested to know that T X’s \omit,
EE\span and \multispan should work in \IEEEeqnarraybox, but not in\IEEEeqnarray because of the need to track column usage with a hidden
counter.

SHELL: HOW TO USE THE IEEETRAN LATEX CLASS

family which provides its own ways of doing these types ofthings. In particular, \cline is totally incompatible — users
should use the \IEEEeqnarraymulticol{num_cols}{h}{} command instead. However, \vline and \hline should
work — unless another LATEX package redefines them in someincompatible way. The IEEEeqnarray family provides its own
version of \vline:\IEEEeqnarrayvrule[rule_thickness]

which produces a vertical rule extending from the top tobottom of a cell without overriding the column type. The
optional argument is for specifying the rule thickness which
defaults to \arrayrulewidth if no argument is provided.
The IEEEeqnarray row commands (discussed in the next
section) provide some alternatives to \hline.
L. Row Commands
The IEEEeqnarray family has several commands that canbe used to produce special rows which span all the columns.
Unless otherwise noted, the commands described here mustissued as the very first command in a given row.
To produce a spacer row which relies on the strut system,
use\IEEEeqnarrayseprow[height][decl]

The first argument specifies the height of the strut row, if left
blank or empty, the default value of 0.25\normalbaseli
neskip will be assumed. The second optional argument isfor commands which will be executed prior to the evaluationof the first argument as is done with \IEEEeqnarraystrut
size. \IEEEeqnarrayseprow will not interrupt the column
definitions, so it will not cut vertical lines. If column definitionsuspension is desired, use the cutting form which will override
all the column types in the entire row:
\IEEEeqnarrayseprowcut[height][decl]

To produce a horizontal rule row, use:
\IEEEeqnarrayrulerow[rule_thickness]

which will override all the column definitions with one that
produces a horizontal rule. If the optional rule thickness is not
specified, the value of \arrayrulewidth will be used.
To produce a double rule row, use:
\IEEEeqnarraydblrulerow[rule_thickness][spacing]which will produce a rule row, a (noncutting) separation row,followed by another rule row. If the optional rule thickness is
not specified, the value of \arrayrulewidth will be used
when producing each of the two rule rows. If the optional
separation distance is not specified, the value of \doubleru
lesep will be used. There is also a cutting form:

19

M. Useful Low Level TEX Commands
Although the use of lower level TEX commands is generally
frowned upon in LATEX, some of them are just too helpful toignore.
\phantom{} produces an invisible box with the width,height and depth of its contents, but the contents themselves
will not appear in the output. There is also the \hphantom{} and \vphantom{} forms which retain only the contents’width, or its height and depth, respectively. As an example,
look carefully at the footnotes at the bottom of Table V. This
table was produced using the \IEEEeqnarraybox command.
The footnotes are actually contained within the last two rowsof the table. Note how the left sides of the footnotes line
up, even though the first one has a superscript asterisk for afootnote symbol. The reason that the second row lines up isbecause, at its left side, it employs a horizontal phantom of
the very same symbol:\hphantom{\textsuperscript{*}}Vertical phantoms can be used to equalize row height or
spacing — such as to get matrices that fit within bracketsof the same size even though one has “tall” symbols and theother not.
The opposite of \hphantom{} is \rlap{} which displays
its contents, but with zero width. There is also an \llap{}which does the same thing, but the contained object will appear
just to the left of the given point, rather than after as with\rlap. For example, look closely at the first “Width” column
heading in Table V. The word “Width” is centered irrespectiveof the asterisk. That is because the width of the asterisk was
zeroed:Width\rlap{\textsuperscript{*}}

The vertical analog of \rlap is \smash{} which reduces theapparent height and depth of its contents to zero. (LATEX’s\raisebox{0pt}[0pt][0pt]{} does about the same thing,
and also provides an adjustable vertical offset.) \smash canbe used when space is already reserved for an object, butthat LATEX does not “know” this and would allocate unwanted
additional vertical space. One good use of smash for tableobjects that are to be “slipped” into a hidden row of zeroheight, or into a row which is to be no higher than the “short”
things, such as horizontal rules, that are in its other columns.
The TEX \noalign{} command can be used within IEEEeqnarray family to inject text which is outside of the alignment
structure. For example,\begin{IEEEeqnarray}{rCl}
A_1&=&7\IEEEyessubnumber\\
A_2&=&b+1\IEEEyessubnumber\\\noalign{\noindent and\vspace{\jot}}A_3&=&d+2\IEEEyessubnumber%\end{IEEEeqnarray}

produces\IEEEeqnarraydblrulerowcut[rule_thickness][spacing]which works the same way except that the separation row
will override all the column definitions. (Vertical rule columns
will not appear inside the double rule row produced by thiscommand.)A1 = 7(3a)A2 = b + 1(3b)A3 = d + 2

(3c)

and

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JOURNAL OF LATEX CLASS FILES, VOL. 1, NO. 11, NOVEMBER 2002

When employed, \noalign must be the very first commandin a row — even before any \IEEEeqnarraymulticol,\IEEEeqnarrayomit, or row commands.
Be forewarned that the proper use of \noalign can betricky. There are three potential issues. (1) Remember that
\noalign will place its contents outside of the alignment.
So, the line spacing controls of the IEEEeqnarray commands
will not be in effect. The user may have to manually add \baselineskip and/or \jot spacing as needed (which was donein the previous example). (2) Furthermore, \noalign does
not automatically place its contents within a box. However,nonaligned material must be placed within a horizontal box
when within the vertical box produced by the \IEEEeqnarr
aybox command. Therefore, when using \noalign withina \IEEEeqnarraybox, be sure to wrap things up in an\hbox{}:21\noalign{\hbox{and therefore}}(3) Finally, there may be some issues related to how easily
page breaks occur around the \noalign lines. This is only
an issue with \IEEEeqnarray because page breaks cannot
occur within the box produced by \IEEEeqnarraybox. Ifneeded, page break desirability can be altered by manuallyentering \pagebreak, or \nopagebreak, etc., at the end of
the \noalign contents.
N. More Practical Examples of Use
The use of the IEEEeqnarray is somewhat complicated.
However, once the building blocks and core concepts areunderstood, the user may find that is easier to use theIEEEeqnarray family for just about every alignment situation
rather than to have to remember all the interfaces and uniquebehaviors of many different tools.
A few “real world” examples will now be demonstrated.
1) IEEEeqnarray Cases Structures: Cases structures can beobtained using \IEEEeqnarraybox:x,
for x ≥ 0
(4)|x| =−x, for x < 0which was produced using the code:\begin{equation}\setlength{\nulldelimiterspace}{0pt}|x|=\left\{\begin{IEEEeqnarraybox}[\relax][c]{l’s}x,&for $x \geq 0$\\-x,&for $x < 0$%\end{IEEEeqnarraybox}\right.
\end{equation}

Note the use of the large \quad (1 em) spacing before theconditional statements. The zeroing of \nulldelimiterspa
ce, an optional step, eliminates the width of the nonvisible
closing brace “\right.” in order to perfectly center thevisible portion of the equation.22
Note that both branches share a common equation number.
If an equation (sub)number is wanted for each branch, thepreferred solution is to use the cases.sty package as discussed
21 LAT X’s \mbox will not work!

E

22 The width of null delimiters is typically only 1.2 pt, and so can usually

be safely ignored.

in Section VIII-A. However, it is possible to use \IEEEeqn
array to build such a thing — although it takes extra workand a few tricks to do so. For example,x,
for x ≥ 0
(5a)
|x| =
−x, for x < 0(5b)
was produced using the code:\begin{IEEEeqnarray}[\setlength{\nulldelimiterspace}{0pt}]{rl’s}&x,&for $x \geq 0$\IEEEyessubnumber\\*[-0.625\normal
baselineskip]\smash{|x|=\left\{\IEEEstrut[3\jot][3\jot]\right.}&&\nonumber\\*[-0.625\normalbaselineskip]&-x,&for $x < 0$\IEEEyessubnumber\end{IEEEeqnarray}

A hidden middle row is used to hold the left hand side ofthe equality. In order to prevent this row from altering the
spacing between the two branches, its height must be smashedand the extra line spacing (which consists of \baselinesk
ip, plus \jot which is normally 0.25\baselineskip forIEEEtran.cls.) must be removed, half from above and half frombelow, — making it look as though the middle row neveroccurred. Because the large brace cannot “see” the height ofthe branches, it must be manually sized with a strut. The
star form of the new line commands is used to prevent thepossibility of a page break within the structure.
2) Matrices: Displayed matrices can easily be created with\IEEEeqnarraybox:!
1 0 0
I= 0 1 0(6)
0 0 1
The code of this example is quite simple:\begin{equation}
I = \left(\begin{IEEEeqnarraybox*}[][c]{,c/c/c,}
1&0&0\\
0&1&0\\
0&0&1%\end{IEEEeqnarraybox*}\right)\end{equation}

Because the example matrix has elements of normal height,
one can use the star form of \IEEEeqnarraybox to turn off
the extra \jot component of the line spacing so as to makea more compact matrix. If larger symbols had been used in
the matrix, the nonstar form would be the better choice. \arraycolsep typically serves quite well as an element column
separator. A standard small math space is added to the endsof the matrix to provide a little distance between it and its
enclosing parentheses.
It is instructive to show how to construct a “small” matrix23 ,
h
i
1/2 0
S = 0 3/4
(7)which was produced via\newcommand{\mysmallarraydecl}{\renewcommand{%\IEEEeqnarraymathstyle}{\scriptscriptstyle}%\renewcommand{\IEEEeqnarraytextstyle}{\scriptsize}%\renewcommand{\baselinestretch}{1.1}%
23 IEEE authors should note that the use of small matrices is not recommended as IEEE does not usually reduce font sizes in equations or alter themain text baselineskip to accommodate in-text mathematics.

SHELL: HOW TO USE THE IEEETRAN LATEX CLASS21

TABLE VI

TABLE VIIN ETWORK D ELAY AS A F UNCTION OF L OAD

P OSSIBLE Ω F UNCTIONS

β
1
10
100
*

Average Delayλmin λmax
0.057
0.124
0.830

0.172
0.536
0.905*

Range

Ω(m)

x<0

Ω(m) =

x≥0Ω(m) =

m
X

K −i

i=0

√

m

limited usability\settowidth{\normalbaselineskip}{\scriptsize\hspace{\baselinestretch\baselineskip}}%\setlength{\baselineskip}{\normalbaselineskip}%\setlength{\jot}{0.25\normalbaselineskip}%\setlength{\arraycolsep}{2pt}}%\begin{equation}
S=\left[\begin{IEEEeqnarraybox*}[\mysmallarraydecl][c]{,c/c,}
1/2&0\\
0&3/4%\end{IEEEeqnarraybox*}\right]\end{equation}

The use of a user defined command, \mysmallarraydecl, to contain the IEEEeqnarray setup code, demonstrates
how users can easily recreate their most commonly usedstructures by fully exploiting the on-the-fly configurability of
the IEEEeqnarray family.
This example is more complex than need be in order todemonstrate a few techniques. It would be easy enough to set\baselineskip to the desired value, but suppose that thematrix rows are to be spaced some multiple of the \baselin
eskip of the \scriptsize font. Complicating matters evenmore is the fact that most LATEX class files will not allow theuser to execute text font size commands within math mode
— and the matrix is within an equation. So, \scriptsize
cannot be used to directly set the \baselineskip.
The first step is to set the math and text columns totheir desired styles. Then \baselinestretch is setup to be
used like \arraystretch. The trick is to run \scriptsize
within a \settowidth command which stores the \basel
ineskip of the \scriptsize font, multiplied by \baseli
nestretch, in \normalbaselineskip which is then used
to set \baselineskip, \jot, etc. Finally, \arraycolsep isreduced to better suit the smaller font. Note the use of “%”to prevent unwanted spaces from appearing after the braces atthe end of lines in \mysmallarraydecl.
3) Tables: Tables, especially those with lines, tend to be alittle more complicated. Table VI was made with the followingcode:\begin{table}\centering\caption{Network Delay as a Function of Load}\label{table_delay}\begin{IEEEeqnarraybox}[\IEEEeqnarraystrutmode\IEEEeqnarraystrutsizeadd{2pt}{0pt}]{x/r/Vx/r/v/r/x}\IEEEeqnarraydblrulerowcut\\&&&&\IEEEeqnarraymulticol{3}{t}{Average Delay}&\\&\hfill\raisebox{-3pt}[0pt][0pt]{$\beta$}\hfill&&\IE
EEeqnarraymulticol{5}{h}{}%\IEEEeqnarraystrutsize{0pt}{0pt}\\&&&&\hfill\lambda_{\mbox{min}}\hfill&&\hfill\lambda_{\mbox{max\vphantom{i}}}\hfill&\IEEEeqnarraystrutsizeadd{0pt}{2pt}\\\IEEEeqnarraydblrulerowcut\\&1&&&
0.057&& 0.172&\\&10&&& 0.124&& 0.536&\\&100&&& 0.830&& 0.905\rlap{\textsuperscript{*}}&\\\IEEEeqnarraydblrulerowcut\\&\IEEEeqnarraymulticol{7}{s}{\scriptsize\textsuperscript{*}limited usability}%\end{IEEEeqnarraybox}\end{table}

Because this table has lines, the first step is to enable strut
mode line spacing. The strut height is then increased by acouple of points to provide a little more headroom above theletters.24 This table uses cutting horizontal rules and open
sides as is commonly done in IEEE publications. There arethree extra “x” columns which serve as place holders. The“x” columns at each end serve as a quick way to get thehorizontal rules to extend a little past the contents of the table.
The middle “x” column serves as an attachment point for thehorizontal rule that is below “Average Delay.” Without thisextra column, the left side of that horizontal rule would cut
into the middle double vertical rule.25 Notice how the “β” issmuggled in as part of the row containing the horizontal rule.
β has to be smashed so that it will not add unwanted verticalspacing. Likewise, the strut for that row is disabled. Also, \raisebox is used instead of \smash so that β can be verticallylowered — otherwise it would appear on its baseline whichis too high for the purpose at hand. The \hfill on eitherside of β changes the justification of that cell to centered.
The “min” and “max” subscripts would not normally sit at
the same level because the “i” in min is slightly higher thanthe letters in “max”. To fix this, a \vphantom “i” is added to“max”. Because these subscripts sit so low, the depth of thatline’s strut is increased a couple of points. Alternatively, one
could have just smashed the “i”. The asterisk next to “0.905”
is reduced to zero width via \rlap so that it will not affect its
cell’s width or alignment. This example also illustrates how
to integrate table footnotes into the end of a table without thehelp of external packages.
Strut spacing does not work so well for rows that containtall symbols because such objects routinely exceed the heightof the struts. Furthermore, increasing the strut height is often
not an option because (1) the height and depth of the tall
symbols must be measured or guessed; and (2) there may beother rows which have normal line height. Table VII illustrates
such a situation. Its code is shown here:
24 Knuth calls this extra step a mark of quality.
25 Some may even think it would be better that way, but we want to show
some tricks in these examples.

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JOURNAL OF LATEX CLASS FILES, VOL. 1, NO. 11, NOVEMBER 2002

\begin{table}\centering\caption{Possible $\Omega$ Functions}\label{table_omega}\begin{IEEEeqnarraybox}[\IEEEeqnarraystrutmode\IEEEeqnarraystrutsizeadd{2pt}{1pt}]{v/c/v/c/v}\IEEEeqnarrayrulerow\\&\mbox{Range}&&\Omega(m)&\\\IEEEeqnarraydblrulerow\\\IEEEeqnarrayseprow[3pt]\\&x < 0&&\Omega(m)=\sum\limits_{i=0}ˆ{m}Kˆ{-i}&\IEEEeqnarraystrutsize{0pt}{0pt}\\\IEEEeqnarrayseprow[3pt]\\\IEEEeqnarrayrulerow\\\IEEEeqnarrayseprow[3pt]\\&x \ge 0&&\Omega(m)=\sqrt{m}\hfill&\IEEEeqnarraystru
tsize{0pt}{0pt}\\\IEEEeqnarrayseprow[3pt]\\\IEEEeqnarrayrulerow\end{IEEEeqnarraybox}\end{table}

The solution is to use \IEEEeqnarrayseprow to manually
add in a fixed amount of extra space as needed. In this way,
\IEEEeqnarrayseprow can do for lined tables what \jotdoes for multiline equations. Of course, using this method, thebaselines of the rows will no longer be equally spaced.
The \hfill in the square root cell is a cheap, but effective,
way of getting the equal signs to line up without the need ofadditional columns.
ACKNOWLEDGMENT
The author would like to thank Laura Hyslop, Cathy Cardon
and Ken Rawson of the IEEE for their help and support
in making this work possible. The knowledge and priorwork of TEX gurus such as Donald Arseneau, Fred Bartlett,David Carlisle, Tony Liu, Frank Mittelbach, Piet van Oostrum,
Roland Winkler and Mark Wooding were instrumental in developing the complex IEEEeqnarray family of commands. The
author is also grateful to Peter Wilson and Donald Arseneau
for allowing the inclusion of their \@ifmtarg command.
Finally, this work might not have been possible had it
not been for the efforts of the prior IEEEtran developers:
Gerry Murray, Silvano Balemi, Jon Dixion, Peter Nüchter andJuergen von Hagen. Their work still lives on to some degree
within IEEEtran.

[9] D. Arseneau. (2002, May) The cases.sty package. [Online]. Available:
http://www.ctan.org/tex-archive/macros/latex/contrib/other/misc/[10] D. Carlisle. (2001, Sept.) Packages in the ‘graphics’ bundle.
grfguide.ps. [Online]. Available: http://www.ctan.org/tex-archive/
macros/latex/required/graphics/[11] K. Reckdahl. (1997, Dec.) Using imported graphics in LATEX 2ε .
esplatex.ps or epslatex.pdf. [Online]. Available: http://www.ctan.org/
tex-archive/info/[12] C. Barratt, M. C. Grant, and D. Carlisle. (1998, May) The psfrag.sty
package. [Online]. Available: http://www.ctan.org/tex-archive/macros/
latex/contrib/supported/psfrag/[13] F. Mittelbach and D. Carlisle. (2001, Sept.) The array.sty
package. [Online]. Available: http://www.ctan.org/tex-archive/macros/
latex/required/tools/[14] D. Arseneau. (1999, May) The threeparttable.sty package. [Online].
Available: http://www.ctan.org/tex-archive/macros/latex/contrib/other/misc/[15] S. D. Cochran. (2002, Apr.) The subfigure.sty package. [Online]. Available: http://www.ctan.org/tex-archive/macros/latex/contrib/
supported/subfigure/[16] S. Tolušis. (1999, Oct.) The stfloats.sty package. Documentation
is in the stfloats.sty comments in addition to the presfull.pdf
file. [Online]. Available: http://www.ctan.org/tex-archive/macros/latex/
contrib/supported/sttools/[17] D. Carlisle. (1998, Aug.) The fix2col.sty package. [Online]. Available:
http://www.ctan.org/tex-archive/macros/latex/contrib/supported/carlisle/[18] M. Shell. (2002) The IEEEtran BIBTEX style. [Online]. Available:
http://www.ctan.org/tex-archive/macros/latex/contrib/supported/
IEEEtran/bibtex[19] P. W. Daly. (1999, Feb.) The balance.sty package. [Online]. Available:
http://www.ctan.org/tex-archive/macros/latex/contrib/other/preprint/[20] S. Tolušis. (1997, Oct.) The flushend.sty package. Documentation
is in the flushend.sty comments in addition to the presfull.pdf
file. [Online]. Available: http://www.ctan.org/tex-archive/macros/latex/
contrib/supported/sttools/[21] M. Shell. (2002) The testflow diagnostic suite. [Online]. Available: http://www.ctan.org/tex-archive/macros/latex/contrib/
supported/IEEEtran/testflow[22] D. Arseneau. (1999, Mar.) The url.sty package. [Online]. Available:
http://www.ctan.org/tex-archive/macros/latex/contrib/other/misc/[23] M.
Shell.
(2002)
The
IEEEtrantools.sty
package.
[Online]. Available: http://www.ctan.org/tex-archive/macros/latex/contrib/
supported/IEEEtran/tools

R EFERENCES[1] M. Shell. (2002) IEEEtran homepage on CTAN. [Online]. Available: http://www.ctan.org/tex-archive/macros/latex/contrib/
supported/IEEEtran/[2] (2002) The IEEE website. [Online]. Available: http://www.ieee.org/[3] H. Kopka and P. W. Daly, A Guide to LATEX, 3rd ed. Harlow, England:
Addison-Wesley, 1999.
[4] R. Fairbairns. (2002) The TEX FAQ. [Online]. Available: http://www.tex.ac.uk/cgi-bin/texfaq2html[5] A. Gefen, “Simulations of foot stability during gait characteristic ofankle dorsiflexor weakness in the elderly,” IEEE Trans. Neural Syst.
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[6] D. Arseneau. (2001, Nov.) The cite.sty package. [Online]. Available:
http://www.ctan.org/tex-archive/macros/latex/contrib/supported/cite/[7] (2000, July) The amsmath.sty package. The American MathematicalSociety. [Online]. Available: http://www.ctan.org/tex-archive/macros/
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supported/mdwtools/

Michael Shell (M’87) received the B.E.E. and
M.S.E.E. degrees in electrical engineering from theGeorgia Institute of Technology, Atlanta, in 1991
and 1993, respectively, and is currently working
toward the Ph.D. degree. He has developed several
all-optical packet-switched network subsystems andnode demonstrations and is currently working on
new analysis tools and techniques for the opticalshared memory architecture class of packet switches.
His research interests include all-optical packetswitched networks, high speed opto-electronic interface design, discrete simulation and exact Markov models for buffered packet
switches.
Mr. Shell is also the author of the most recent versions of the IEEEtran
LATEX class and BIBTEX style packages and is the current maintainer of both.