HDTenEightyP/NetNews huggingface dataset:
From: andrew@rentec.com (Andrew Mullhaupt)
Newsgroups: sci.math.num-analysis
Subject: Re: SVD row update
Date: 21 Jul 92 15:05:05 GMT
Organization: Renaissance Technologies Corp., Setauket, NY.

In article <sjreeves.920720112016@fourier.ee.eng.auburn.edu> sjreeves@eng.auburn.edu (Stan Reeves) writes:
>
>Does anyone know of an efficient method for updating an SVD of a matrix
>when a new row is added to the matrix?  By "efficient," I mean something
>more efficient than just redoing the SVD from scratch.  Any help would
>be appreciated.

When the matrix is long and skinny, (as will eventually obtain when you
keep adding rows), you can use the R-SVD and update the initial QR
decomposition. You still have to do the little SVD, but the work is
dominated (in the limit) by the QR update. So, to the extent that you
consider QR updates 'fast' and 'reliable', you can update the SVD. It
is at least faster than doing it from scratch.

Hanson and Lawson, and Golub and van Loan discuss QR updates.

Later,
Andrew Mullhaupt
From: lexier@fraser.sfu.ca (Lyle Lexier)
Subject: Math software for a mathematical pendulum of length L and mass m
Organization: Simon Fraser University, Burnaby, B.C., Canada
Date: Wed, 22 Jul 1992 02:32:20 GMT

     Hello everyone,
 
     Is there any software for calculating the differential equation:
 
                    g
          fi  =   - - sin (fi)
            tt      L

     Much help would be appreciated.
 
     Lyle

-- 
--------------------------------------------------------------------------------
|  Lyle Lexier        | There should be no discrimination against any person   |
|lexier@fraser.sfu.ca | for his/her race, sex, or sexual orientation.          |
--------------------------------------------------------------------------------
Newsgroups: sci.math.num-analysis
From: mml@eng.umd.edu (Marios Leventopoulos)
Subject: Code for All Basic Feasible solutions of a LPP
Date: Wed, 29 Jul 92 14:13:17 GMT
Organization: College of Engineering, University of Maryland, College Park
Keywords: Linear Programming, Basic Feasible Solutions
Originator: mml@hellas.eng.umd.edu


I would appreciate if someone could provide me with a reference/pointers to 
a code (or at least an algorithm) that explores all the basic feasible solutions
of a linaer programming problem (i.e. of a convex polytope).

Thanks
-marios

mml@eng.umd.edu
From: rlr@acsu.buffalo.edu (Raymond Roskwitalski)
Newsgroups: sci.math.num-analysis
Subject: Krylov subspace
Date: 22 Jul 92 16:44:11 GMT
Organization: UB
Originator: rlr@bromine.chem.buffalo.edu


I am looking for information on how to construct a Krylov subspace in order to 
diagonalize a 4851 by 4851 matrix. I am interested only in the "lowest "
eigenvalues and eigevectors. Any references would be greatly appreciated.
Thanks in advance.

Raymond Roskwitalski, Jr.
rlr@hydrogen.chem.buffalo.edu
July 22, 1992
Newsgroups: sci.math
From: dan@kfw.COM (Dan Mick)
Subject: Useful function with odd? properties
Reply-To: dan@kfw.com (Dan Mick)
Organization: KFW Corporation, Newbury Park, CA
Date: Wed, 29 Jul 92 02:22:44 GMT


We need a function to generate serial numbers.  Useful properties
of this function:

- It should provide a one-to-one mapping from positive integers in
  [0, limit) to positive integers in [0, limit).

- It should not exhibit easily seen correlation to the input; for instance,
  f(x) = x and f(x) = 2x MOD limit are not acceptable.

- It should be easy, or at least reasonably fast with average computer 
  hardware, to determine x given f(x) (the inverse function).

I've thought of various hashing algorithms and encryption routines to try to
use something I've already got, but I don't see that anything fits the 
requirements very well.

Can anyone help?  Can anyone suggest a better newsgroup for this kind of
request, or am I in the right pub here?


*****************************************************************************
*                                                                           *
*   Please email responses to dan@kfw.com...I don't receive sci.math yet    *
*                                                                           *
*****************************************************************************
Newsgroups: sci.math
From: keithw@ccorp.uucp (Keith Weintraub - dpr2)
Subject: Calculus of Variations?
Organization: Citicorp, New York City
Date: Thu, 23 Jul 92 12:28:43 GMT

Netfolk,
	I am working on forward rate curve construction and would like to
solve a problem that I think is of "Calculus of Variations" type. Feel free
to correct me if I am wrong. I would like to find a *continuous* non-negative
function y(t) whose derivative has minimum L_2 norm over [0,T] and integrates
to given constants over disjoint subintervals that cover [0,T]. (I wanted to
write that in English---hope I succeeded---in case people don't like the TeX
notation below). More symbolically I would like to find a *continuous*
function y(t) such that

	\int_0^T (y'(s))^2 ds

is a minimum subject to the constraints

	\int_{t_{i-1}}^{t_i} y(s) ds = a_i > 0 (a_i known) i = 1,...,n

where
	0 = t_0 < t_1 < ... < t_n = T.

Any guidance, references, solutions would be most appreciated.

Respond by e-mail or post and if I get anything interesting I will post a
summary.

Thanks in advance,
KW

Newsgroups: dead.article
Subject: Calculus of Variations?

Netfolk,
	I am working on forward rate curve construction and would like to
solve a problem that I think is of "Calculus of Variations" type. Feel free
to correct me if I am wrong. I would like to find a *continuous* non-negative
function y(t) whose derivative has minimum L_2 norm over [0,T] and integrates
to given constants over disjoint subintervals that cover [0,T]. (I wanted to
write that in English---hope I succeeded---in case people don't like the TeX
notation below). More symbolically I would like to find a *continuous*
function y(t) such that

	\int_0^T (y'(s))^2 ds

is a minimum subject to the constraints

	\int_{t_{i-1}}^{t_i} y(s) ds = a_i > 0 (a_i known) i = 1,...,n

where
	0 = t_0 < t_1 < ... < t_n = T.

Any guidance, references, solutions would be most appreciated.

Respond by e-mail or post and if I get anything interesting I will post a
summary.

Thanks in advance,
KW

-- 
Keith Weintraub (KW) -- Citicorp |    I told you a trillion times:
keithw@Citicorp.COM              |	"Don't exaggerate."
uunet!ccorp!keithw               |
Organization: University of Illinois at Chicago
Date: Wednesday, 29 Jul 1992 21:43:42 CDT
From: <U53644@uicvm.uic.edu>
Newsgroups: sci.math
Subject: Re: Journal prices (was: Gordon & Breach suit against AMS
 <14pivtINNp4d@function.mps.ohio-state.edu>

You know, there is the small matter here of there being more Statisticians
than applied analysts (yes, I know that Stats can be viewed as a branch of
applied measure theory, but that doesn't change the fact that more people will
be interested in the material covered in J. American Statistical Association
than in Applicable Analysis). I don't think that comparisons between the two
Journals can tell one much.

                                               Joseph B. Dunphy
From: cjh@tinton.ccur.com (Christopher J. Henrich)
Newsgroups: sci.math
Subject: Re: Some musings on expensive journals
Date: 24 Jul 92 22:21:59 GMT
Organization: Concurrent Computer Corp., Tinton Falls, NJ

In article <14maptINNsdv@function.mps.ohio-state.edu> edgar@function.mps.ohio-state.edu (Gerald Edgar) writes:
>In article <BrtKAq.MH3@news.cso.uiuc.edu> sbrown@symcom.math.uiuc.edu (Scott Brown) writes:
>>      On a related note: does anyone know if there is any
>>information as to which journals are the most expensive per
>>page?
>
>I seem to recall that the AMS published a list of this information,
>and one of the publishers took them to court to stop it...
>
>Or does my memory have this garbled?
>
No.  This happened in 1991, I think.  The publisher was
Gordon&Breach, and apparently they sued the AMS for libel,
or threatened to do so.  An account, with a letter from somebody at
G&B, appeared in the _Notices_.  

Anybody know if the suit was continued? Or settled?

Regards,
Chris Henrich
Newsgroups: sci.math
From: sbrown@symcom.math.uiuc.edu (Scott Brown)
Subject: Some musings on expensive journals
Organization: University of Illinois at Urbana
Date: Thu, 23 Jul 1992 02:01:37 GMT

Regarding the issue of the expense involved in maintaining
an up-to-date journal library:

      In response to the suggestion that putting journals
on-line instead of hardcopy would solve the problem, I
hope that I am not alone in voicing a resounding *NONONO!*
Pleez O Pleez no! Why? For starters, I cannot imagine that
it would be nearly as conducive to perusing journals as the
hardcopy is.  There is a joy in wandering through a crowded
library stacks with half an hour to kill, selecting a journal
at random from a field of interest, and skimming the contents;
many's the time I have discovered a useful tidbit in this
fashion, or stumbled across some previously unmown to me 
article which set me on a hunt for more information. Try
as I might, I cannot reproduce this effect on-line, be it
reading newsgroups, examining source code, using MathSciDisk,
or whatever.  Until monitors 2meters by 3meters are the norm,
I can't see any practical way to reproduce this electronically.


      On a related note: does anyone know if there is any
information as to which journals are the most expensive per
page? per subscribing institution?

scott brown

Newsgroups: sci.math
From: chepan@gsusgi1.gsu.edu (Parthasarathy Nambi)
Subject: Primes with 'n' digits?
Summary: Primes with n digits.
Keywords: primes
Organization: Georgia State University
Date: Fri, 31 Jul 1992 18:23:29 GMT


 Hi,

 Is there a formula (or papers that address the following question)
 to find out how many primes are there with *n* digits?

 For example there are four primes with one digit (2,3,5 and 7)
 there are 21 primes with two digits etc.

 How about for any n, where n is the number of digits?

 Please post your responses here.          

 P. Nambi


Newsgroups: sci.math
From: das50852@uxa.cso.uiuc.edu (dan)
Subject: Re: An interesting limit problem.
Organization: University of Illinois at Urbana
Date: Mon, 27 Jul 1992 14:38:16 GMT

mattm@lure.latrobe.edu.au writes:

>A challenge to all mathematicians. A 100 years ago, this would probably have 
>been solved fairly simply in a natural way, but can you? I think that this
>problem was first posed by the Russian mathematician Arnold. Hope you find this
>problem as interesting as I did when I first solved it.

>                sin(tan x)    -    tan(sin x)
>	lim  ----------------------------------  = ???
>	x->0 arcsin(arctan x) - arctan(arcsin x)


Hmmmm, Mathenatica likes this:

In[1]:= f[x_] = Sin[Tan[x]]-Tan[Sin[x]]
Out[1]= Sin[Tan[x]] - Tan[Sin[x]]

In[2]:= g[x_] = ArcSin[ArcTan[x]] - ArcTan[ArcSin[x]]
Out[2]= ArcSin[ArcTan[x]] - ArcTan[ArcSin[x]]

In[3]:= Limit[ f[x]/g[x], x->0]
[Dan counts as the NeXT humms; only got to 2 though]
Out[3]= 1

Will someone please back me up, and say that no one learning
Calculus should ever be allowed anywhere _NEAR_ Mathematica?
(When I say 'learning Calculus' I mean the first two or three
semesters) I watched one of my roomates struggle thru his
second and third semesters of 'Calculus and Mathematica', and
it seemed that the basics got skipped, so that the stuff for
which Mathematica is useful was just more confusing. Any thoughts?


				dan simms

-----
artie@uiuc.edu
From: fc03@ns1.cc.lehigh.edu (Frederick W. Chapman)
Newsgroups: sci.math
Subject: Re: Group Theory Question
Date: 24 Jul 92 17:54:34 GMT
Organization: Lehigh University

In article <36049@sdcc12.ucsd.edu>, dmassey@sdcc3.ucsd.edu (Daniel
Massey) writes:

>Hi,
>I'm reviewing algebra and have gotten stuck on the following
>seemingly simple question:
>
>G is an abelian group and H a subgroup  of G. Prove their exists
>a subgroup of G which is iso. to G/H.
>
>Anyway, I'm not making any progress on this one so any suggestions
>would be greatly appreciated.
>Thanks,
>Dan Massey


That's because the statement is... FALSE!  Take G to be the additive group
of the integers Z, and take H to be the subgroup of even integers 2Z.  Then
G/H = Z/2Z, which is isomorphic to C_2, the cylic group of order 2.  Z/2Z
contains an element of order 2, namely 1+2Z, but Z contains no elements of
order 2 (every non-zero element of Z has infinite order).

I believe the proposition may be true for FINITE abelian groups.  I think
that an easy proof should follow from the fundamental theorem for finite
abelian groups (though perhaps that is overkill).  Start by showing that
the proposition is true for cyclic groups of prime power order, and then
use the fundamental theorem for finite abelian groups in conjunction with
the fact that (G_1 (+) ... (+) G_n) / (H_1 (+) ... (+) H_n) is isomorphic
to (G_1/H_1) (+) ... (+) (G_n/H_n) if H_i is a normal subgroup of G_i for
each i; replace the G_i/H_i's by subgroups J_i's of the G_i's (by the
result for cyclic groups of prime power order), and you are done!  The only
other part necessary is to show that a subgroup H must have the structure
described above (i.e., that the H_i's are subgroups of the G_i's).
-- 

o ------------------------------------------------------------------------- o
|  Frederick W. Chapman, User Services, Computing Center, Lehigh University |
|    Campus Phone:  8-3218     Preferred E-mail Address:  fc03@Lehigh.Edu   | 
|  "I do comedy and magic; what you don't find funny -- that's the magic."  |
o ------------------------------------------------------------------------- o
Newsgroups: sci.math
From: rickertj@athena.cas.vanderbilt.edu (John Rickert)
Subject: Re: Math or Maths
Organization: Vanderbilt University Mathematics Department
Date: Sat, 25 Jul 92 19:49:39 GMT

In article <4584@daily-planet.concordia.ca> mckay@alcor.concordia.ca ( John Mckay ) writes:
>
> The Greek is MATHEMATIKOS - when did the abbreviations first occur?
>
>
>  

    Actually, it went more by "he mathematike techne" -- "the mathematical
art."  That would, incidentally, make it singular.  There is also the
Greek word "MATH" (last letter eta).  It means "folly, idleness, vanity."

    :-)


John R.


Newsgroups: sci.math
From: deghare@daisy.uwaterloo.ca (Dave Hare)
Subject: Mortgage payments, principal and interest
Organization: University of Waterloo
Date: Fri, 31 Jul 1992 18:35:54 GMT

Associated to each mortgage interest rate there is a number which, when
multiplied by the outstanding principal gives the amount of interest to
be paid in the next mortgage payment.  For example, for a rate of 10%, 
the number is  .0979781532.  Thus, if one has a $100,000 principal, and
one pays monthly, then the amount of interest paid on the next payment
will be  100,000 * .0979781532 / 12 = $816.48 , from which one can 
easily determine how much of the principal is being paid (by subtracting
this amount from the total payment).

One of the great benefits :-( of the computer age is that there is now
a large body of "bankers" who are ignorant of this fact, who are surprised
when one informs them of this, and have no idea where to look to find
the numbers associated with the various interest rates.  The computer,
after all, does all the calculations.  What difference does it make if
the people in charge of the computers understand what the computer is
doing?

When I first got my mortgage, the rate was 10.75%, and the corresponding
factor is .1051686384 .  I was able, after some extensive phoning, to 
find a mortgage loan officer at a local bank who could find this information.
The first time I renewed, the rate was 10%, and, with more effort, I was
able to find the number given above.

I have now renewed my mortgage again, and I would like to get the number
corresponding to the new rate, which is 7.5% (I love government economic
policy flip-flops, don't you?).

But what I would really like is a source reference for this.  Is there
a standard book of "banker's tables" that has this information?  And does
anyone know how these numbers are arrived at?  (My guess is a sort of
root-finding scheme, but I'm not sure what the input formula should be.)

Thx for any help.

Dave Hare
Newsgroups: sci.math
From: tycchow@riesz.mit.edu (Timothy Y. Chow)
Subject: Re: Mathematical reality (was: You know, the integers)
Organization: None.  This saves me from writing a disclaimer.
Date: Thu, 23 Jul 92 17:12:32 GMT

In article <COLUMBUS.92Jul23085953@strident.think.com> columbus@strident.think.com (Michael Weiss) writes:

>[discussion by Dan Bernstein and Timothy Y. Chow on whether formalism is
>the "correct" philosophy of mathematics or not-- though they didn't put it
>that way-- omitted]
>
>Gee, do you suppose that Peano, Russell, Brouwer, Hilbert, Godel, and co.
>would have come to an agreement and settled all these questions if only
>they'd had email?

I was tempted to use the word "formalism" in the discussion several times
but refrained because I didn't think it was necessary.  Moreover I was not
attempting to refute formalism but trying to show that there are some
difficulties with formalism and it is not the only philosophy of mathematics
around.  This is a more modest goal and has a fighting chance of being
attained.
-- 
Tim Chow     tycchow@math.mit.edu
Where a calculator on the ENIAC is equipped with 18,000 vacuum tubes and weighs
30 tons, computers in the future may have only 1,000 vacuum tubes and weigh
only 1 1/2 tons.                               ---Popular Mechanics, March 1949
From: davidc@panix.com (David C. Chorlian)
Newsgroups: sci.math
Subject: Re: The Value of Science
Keywords: Relativity, Poincare, Whittaker
Date: 31 Jul 92 03:26:39 GMT
Organization: PANIX Public Access Unix, NYC

In <1992Jul30.105827.6185@Princeton.EDU> greg@phoenix.Princeton.EDU (Gregory Nowak) writes:

>}	Of Poincare's 1904 address in St. Louis, Pais gives the
>}following account on page 128:
>}	"All  phenomena seen by one observer [in relative motion to
>}another] are retarded relative to the other, but they all are
>}retarded equally (Poincare points out) and 'as demanded by the
>}relativity principle [the observer] cannot know whether he is at
>}rest or in absolute mothion.'  Poincare is getting close.  

>Pais' book is nice if you want a good story about Einstein. It falters
>in moments like these, when he steps out of the historian's role and
>decides he has to deify Einstein and refute claims that other
>contemporary actors may have "gotten" relativity. To be fair, some of
>these claims are also rather sloppily formulated.

Can you show a specific inaccuracy in Pais's account?

>}	Although Poincare had the equations of the Lorentz transformation
>}by 1905, HE DID NOT UNDERSTAND WHAT THEY MEANT.  Thus he is rightly
>}not credited with the development of special relativity.

>I feel I have to step in here in my capacity as a historian of

Your capacity is irrelevant; only your cogency counts.

>science. One of the most common mistakes non-historians make about
>Einstein is that they assume the moment the 1905 paper hit the
>presses, everyone saw it as touching off a revolution in physics and
>immediately declared themselves "pro-Einstein" or "anti-Einstein". The

No such assumption is stated or implied in my posting.  Pais
has a short section on the reception of Einstein's work which
claims that it was slow to develop a significant reaction.

>field is a bit more complicated in those first few years, and if one
>wants to be a fair-minded historian one has to avoid handing out
>"right" and "wrong" awards. Einstein developed special relativity,
>true -- but don't imagine from that that Poincare or Lorentwz "didn't
>understand" something. I'd suggest that you check out an article by

The point is that if what Pais says about Poincare's 1908 lectures
in Goettingen is true, then Poincare did not understand the full
implications of the equations he wrote in his 1905 paper, and
Einstein expressed in his 1905 paper a much fuller understanding
of their implications. 
To make a statement like this is not to be giving awards, which
is not a question of fair-mindedness but what makes sense as
history.

>Andrew Warwick which should be appearing soon in Science in Context
>(sorry, I only saw it in preprint) which summarizes the reading of
>Einstein in the Cavendish Labs in the years 1905-1911: In short,
>Einstein's work was seen as _confirming_ that of Larmor. Warwick's
>work serves as a good corrective to the notion that everything was cut
>and dried by 1906.

Again, no such claim is made in my posting.

>greg

David B. Chorlian
Newsgroups: sci.math
From: andyc@eliot.uucp (Andy Panda Collins)
Subject: Complex Analysis
Keywords: i,e,pi
Organization: Systems Center, Inc., Reston, VA, USA
Distribution: na
Date: Thu, 23 Jul 1992 19:57:28 GMT


I've got some questions about complex analysis and I don't have access to a good book store that carries heavy-duty math texts. Can someone suggest some good texts? I have some basic knowledge of the subject, but would like some information on how to analyze complex functions of complex variables. Thanks a bunch. e^(i*_pi_)=(-1)!
From: edgar@function.mps.ohio-state.edu (Gerald Edgar)
Newsgroups: sci.math
Subject: Re: Some musings on expensive journals
Date: 23 Jul 1992 09:05:01 -0400
Organization: The Ohio State University, Dept. of Math.
NNTP-Posting-Host: function.mps.ohio-state.edu

In article <BrtKAq.MH3@news.cso.uiuc.edu> sbrown@symcom.math.uiuc.edu (Scott Brown) writes:
>      On a related note: does anyone know if there is any
>information as to which journals are the most expensive per
>page?

I seem to recall that the AMS published a list of this information,
and one of the publishers took them to court to stop it...

Or does my memory have this garbled?


-- 
  Gerald A. Edgar                Internet:  edgar@mps.ohio-state.edu
  Department of Mathematics      Bitnet:    EDGAR@OHSTPY
  The Ohio State University      telephone: 614-292-0395 (Office)
  Columbus, OH 43210             -292-4975 (Math. Dept.) -292-1479 (Dept. Fax)
From: torkel@sics.se (Torkel Franzen)
Newsgroups: sci.math
Subject: Re: Stupid question about FLT
Date: 21 Jul 92 08:51:26 GMT
	<1992Jul18.212618.15509@mixcom.com> <1992Jul18.224827.2167@sics.se>
	<1992Jul20.035836.4789@mixcom.com> <1992Jul20.080932.24570@sics.se>
	<MARTIN.92Jul20172809@lyra.cis.umassd.edu>
Organization: Swedish Institute of Computer Science, Kista

In article <MARTIN.92Jul20172809@lyra.cis.umassd.edu> 
martin@lyra.cis.umassd.edu (Gary Martin) writes:

   >"Exactly like" in this context means "elementarily equivalent", not
   >"isomorphic".

  I might have assumed that the term "exactly like", which has no
standard mathematical definition, here meant "elementarily eqivalent",
had not the original author gone on to say that "in particular, there
are always models containing natural numbers which are not represented
by any terms of the language."  So, whatever the original intention,
I believe it should be pointed out, so as not to mislead anybody,
that any consistent first order extension of PA will have models containing
individuals not represented by any terms of the language.
Newsgroups: sci.math
Subject: Re: An interesting limit problem.
From: a_rubin@dsg4.dse.beckman.com (Arthur Rubin)
Date: 29 Jul 92 23:03:48 GMT

In <VICTOR.92Jul29153236@terse4.watson.ibm.com> victor@watson.ibm.com (Victor Miller) writes:

>This problem is rather interesting, in that it is true in the
>following general sense: let f and g be distinct elements of k[[x]]
>(the power series ring, k is an arbitray field), which have 0 constant
>term, and linear term x.  Then the Laurent series

>	     f(g(x)) - g(f(x))
>	-------------------------------------
>	f^{-1}(g^{-1}(x)) - g^{-1}(f^{-1}(x))

>starts 1 + ...

That is, assuming f(g(x)) != g(f(x)).
--
Arthur L. Rubin: a_rubin@dsg4.dse.beckman.com (work) Beckman Instruments/Brea
216-5888@mcimail.com 70707.453@compuserve.com arthur@pnet01.cts.com (personal)
My opinions are my own, and do not represent those of my employer.
Our news system is unstable; if you want to be sure I see a post, mail it.