HDTenEightyP/NetNews huggingface dataset:
From: nagrwb@vax.oxford.ac.uk
Newsgroups: sci.math.num-analysis
Subject: Re: HELP!!(Cholesky Decompsition for negative-definite matrix ???)
Date: 22 Jan 93 09:07:01 GMT
Organization: Oxford University VAX 6620

In article <20JAN199313260117@envmsa.eas.asu.edu>, sychen@envmsa.eas.asu.edu (Chen, Shen Yeh) writes:
> 
>    I need to solve a linear system equation. In fact, that's the stiffness
>  matrix [K] from finite element method. The system is like :
>  [K]*{U}={P}.  where [K](nxn)
> 
>    [K] IS ALWAYS SYMETRIC, but not necessarily positive-definite. If it is
>  singular, we think this system to be unstable. Because of the symetry, I
>  always use Cholesky Decompsition to reduce the size of [K]. However, now
>  I have some situation that [K] is negative-definite but I still have to
>  solve the equation. I have not try Gauss method yet, however.
> 
You could try the Bunch-Kaufmann method - see Golub + Van Loan, Matrix
Computations Sec 4.4, 2nd edition, 1989 Software is available in LAPACK
on netlib.
>    Does anyone kow :
>    1) Is there any method I can use to reduce [K], and still solve the system
>       when [K] is negative-definite ? (Note that [K] IS ALWAYS SYMETRIC)
>    2) If such method exists, what's the criteria for positive- or negative-
>       definite?
>    3) If no such method exits,( We can not take advantage of symetry to
>       reduce the size of [k], I mean.), does Gauss method work? What's
>       the criteria for question (2)?
> 
>  NOTE : (1) In such system, we do not do pivotting among the rows of [K],
>             if using Gauss method. If there is a zero on the diagonal,
>             we consider it as unstable.
You will have to pivot.
>         (2)      [ ] ====> matrix      { } ====> column vector
> 
>    It will be greatly appreciated if anyone can give me some idea. If you
>  do not want to type all that stuff to me, just tell me the theorem used.
>  Of course, it will be better if you can tell me reference books. Any
>  assistance will be greatly appreciated.
> 
>    Thank you very very very much !!!!!!
Richard.
-- 
** R.W. Brankin -- Numerical Algorithms Group Ltd. -- nagrwb@vax.ox.ac.uk **
**   suggestions for sig. welcome   --   will need   include<std.discl>   **
Newsgroups: sci.math.num-analysis
Newsgroups: sci.math.num-analysis
Subject: Finite Element Programms
From: <QXW900@psuvm.psu.edu>
Date: Fri, 22 Jan 1993 16:12:59 EST
Organization: Penn State University

I need finite element programms, commercial or non-commercial (non-
commercial would be better) that are suitable for PC users to solve
fluid problems.  Can anyone give me some informatiion on this, or
prividewith the programms?

Thanks.  I would appreciate your help.
Xref: sparky sci.math.num-analysis:3974 sci.engr:2538 sci.engr.mech:845
From: tilo@nmr.lpc.ethz.ch (Tilo Levante)
Newsgroups: sci.math.num-analysis,sci.engr,sci.engr.mech
Subject: Re: Algorithm(s) need for Bessel functions
Date: 26 Jan 93 17:29:44 GMT
Organization: NMR-Group, Physical Chemistry Lab., ETH-Zuerich, Switzerland

In article <1993Jan26.100935.113272@eratu.rz.uni-konstanz.de>, vaxinf@V36.CHEMIE.UNI-KONSTANZ.DE () writes:
|> 
|> In article <1993Jan25.201447.2082@athena.mit.edu>, cai@athena.mit.edu (Liang-Wu Cai) writes:
|> |>Dear netter,
|> |>
|> |> I am in need (badly) of an accurate algorithm Bessel functions of various 
|> |>kinds with real argument and integer order. What I need actually is a 
|> |>algorithm which is able to provide the result with at least 7 significant 
|> |>digits for J_n (z) and Y_n (z) with n <=100 and z <= 100.
|> 
|> Look into Abromowitz/Stegun Handbook of Mathamatical Functions:
|> 
|> 1.) set j(100)=0
|> 2.) set j(99)=1
|> 3.) do recursion to j(0)
|> 4.) calculate the true j(0) in order to define a normalisation faktor
|> 5.) Multiply all value with that factor
|> 
|> You get all values J(0)...j(100) in that way.
|> 
|> Eberhard Heuser-Hofmann

This algorithm (Miller algorithm)
is based on a recurrence relation for besselfunctions.
You can find a detailed description in 

 Computation with recurrence relations
 / Jet Wimp
 Boston a.o. : Pitman, 1984
 XII, 310 p. : tab. ; 24 cm
 (Applicable mathematics series)
 ISBN 0-273-08508-5

Tilo
From: kerr@ux1.cso.uiuc.edu (Stan Kerr)
Newsgroups: sci.math.num-analysis
Subject: Re: Bessel Fcns of 2nd kind of integer order
Date: 27 Jan 93 22:43:23 GMT
Organization: University of Illinois at Urbana

barry@ramsey.cs.laurentian.ca (Barry G. Adams) writes:

>The IMSL special function library doesn't seem to have a routine
>for calculating
>                       Y  (z)
>                         n

>where n is an integer and z = x + iy is a complex number. Does
>anyone know how to do this or do you know of an available routine?

Algorithm 644 from Transactions on Math Software is a massive collection
of portable Bessel function codes by Donald Amos, and includes such	 
routines. You can get the whole thing by sending email to

     netlib@ornl.gov

with the message

    send big644 from toms
or  send 644r from toms

The response will be LARGE (over 600K) and will arrive in pieces.

To be more selective about which routines you want from the set, send
the message

    send index for amos

You'll receive a list of items available in the amos collection; you can
then order individual items with messages like

    send x from amos
-- 

Stan Kerr    
Computing & Communications Services Office, U of Illinois/Urbana
Phone: 217-333-5217  Email: stankerr@uiuc.edu
From: ramos@engr.LaTech.edu (Alex Ramos)
Newsgroups: sci.math.num-analysis
Subject: ?: Differentiation and Newton's method on complex-valued functions
Date: 22 Jan 1993 22:34:48 GMT
Organization: Louisiana Tech University
Distribution: inet
NNTP-Posting-Host: nebula.engr.latech.edu
X-Newsreader: TIN [version 1.1 PL8]


Suppose I have an arbitrary function H(s), which  can be assumed as 
being of the form F(s)/G(s), where F and G are polynomials that very 
likely have complex roots. However, the function is not available in 
explicit form, but it can be numerically evaluated at any point with
calculator's accuracy (12 digits).

I would like to approximate the roots of F(s) and G(s) so as to express
H(s) explicitly in terms of s.
I suppose Newton's method would work satisfactorily,
unfortunately I don't have a clue on how to approximate the derivative
of  a complex-valued function (note that s is complex as well).

Are there any commonly known algorithms for that?

Thanks in advance for any help. (post or e-mail either is fine)

--

/* ramos@engr.Latech.edu                     
                                            
                Fala-se Portugues, tche!     
		English spoken here.
*/ 

Newsgroups: sci.math.num-analysis
From: mosko@sylmar.math.ucla.edu (Bradley Moskowitz)
Subject: Monte Carlo w/quasirandom pts
Keywords: Monte Carlo
Organization: UCLA Mathematics Department
Date: Tue, 26 Jan 93 21:52:17 GMT

I'm curious as to how many people are using so-called quasirandom
sequences of points (such as Halton, Sobol, or Niederreiter) instead
of more traditional pseudorandom points for their Monte Carlo
computations. If anyone is using quasirandom sequences, I'd be interested in
hearing which variety you use, what applications you use it for, and
any comments about their usefulness. Also if anyone has tried to use them
or thought about using them, but decided not to, I'd be interested in why
you decided against them. 
   You can email me any responses, and I will summarize the results that
I get. 
   Also if anyone is curious about quasirandom Monte Carlo methods
I could email you a list of some good references. 

-- Bradley Moskowitz
   UCLA Dept. of Mathematics
   mosko@math.ucla.edu
From: stannaee@eee.bham.ac.uk (Mr. Eric E. Stannard)
Newsgroups: sci.math.num-analysis
Subject: Singular Value Decomposition Algorithm
Date: 22 Jan 1993 14:26:15 GMT
Organization: The University of Birmingham, England
Distribution: inet
NNTP-Posting-Host: annapurna.eee.bham.ac.uk
X-Newsreader: TIN [version 1.1 PL6]



--
Does anyone have or know where to obtain an efficient routine to
calculate the Singular Value Decomposition of a real matrix. The
code would preferably be in C/C++ but Fortran is fine. 
Is there any free library routines available to do this available by
ftp?

Thanks in advance.

EMail: stannaee@eee.bham.ac.uk
Eric Stannard
Research Student
School of Electrical and Electronic Engineering
University of Birmingham
Edgbaston
Birmingham B15 2TT
Newsgroups: sci.math.num-analysis
From: statman@stat.ufl.edu (Chuck Kincaid)
Subject: Questions re convolution in Num. Rec. in C
Organization: University of Fl, Department of Statistics
Date: 27 Jan 93 10:55:09

Hello,
	I have been trying to use the code from the Numerical Recipes
in C book.  I'm not sure which edition (there are two aren't there?) I
copied the code from.  However, I am not getting correct values for the
convolution.  Has anyone had any experience with these routines
(convolution and the fft stuff)?  Are there any bugs in the code?  I've
checked mine with the book a number of times and feel 95% confident that
my code is consistent with the book.  
	Any help is appreciated.  This convolution is a small part in a
bigger program for my research and I've been bogged on it for many weeks
now.  Someone would be much in my debt if they can shed light here.

charles d. kincaid

p.s.  btw, am I alone in believing that the documentation for the code
is very poor.  They do a good job explaining the theory behind the code
(for fft stuff at least), but then they use bad variables and don't
explain why the code works.  It could be just me.  

chuck
--
charles d. kincaid		STATS:  (904) 392-1941
statman@stat.ufl.edu		CIRCA:  (904) 392-2007
'Damn fine coffee...and hot, too!'
From: takriti@engin.umich.edu (samer Takriti)
Newsgroups: sci.math.num-analysis
Subject: Re: Help , Sparse matrix inversion
Keywords: matrix,sparse,inverse
Date: 24 Jan 93 16:12:09 GMT
Article-I.D.: srvr1.1juf4pINNgjb
Distribution: world
Organization: University of Michigan Engineering, Ann Arbor
NNTP-Posting-Host: fly.engin.umich.edu

In article <1993Jan21.125609.27784@rdg.dec.com> shaulz@jeremy.enet.dec.com () writes:
>
>
>Hi!
>I am looking for an efficient algorithms for finding
> the inverse of sparse matrix.
>The matrix has the following structure :
>
> xxxxxx00000...00000xxxxxx0000...000 
> 0xxxxxx00000...00000xxxxxx0000...00
> 00xxxxxx00000...00000xxxxxx0000...0
> .                                 .
> .                                 .
> .                                 .
> xxxxxx00000...00000xxxxxx0000...000 
> 0xxxxxx00000...00000xxxxxx0000...00
> 00xxxxxx00000...00000xxxxxx0000...0
>
>I looked in Numerical Recipes with no result.
>I will appreciate any references to code/algorithms.
>
>Thanks 
> Shaul.

You may want to try SaprcePack. You can get it from Netlib. I think though, that most
of the algorithms of SparcePack are for positive-definite symmetric matrices.
Hope this help.
-Samer
From: drazen@blakey.WPI.EDU (Drazen Beatovic)
Newsgroups: sci.math.num-analysis
Subject: spline intersections ??
Date: 21 Jan 1993 18:44:58 GMT
Organization: Worcester Polytechnic Institute
Distribution: world
NNTP-Posting-Host: blakey.wpi.edu
Oganization: Worcester Polytechnic Institute

Hi,

I am trying to find an intersection of two cubic splines (B-splines,2D).

Any information regarding algorithms or computer codes are appreciated.

Please post or send e-mail to drazen@blakey.wpi.edu

thanks,

Drazen
Newsgroups: sci.math.num-analysis,comp.lang.c++
From: edwin@maui.cs.ucla.edu (Edwin Tisdale)
Subject: Re: newmat07: a matrix package in C++
Organization: UCLA, Computer Science Department
Date: Mon, 25 Jan 93 02:01:47 GMT

In article <C1CqJB.G7F@comp.vuw.ac.nz>
robertd@kauri.vuw.ac.nz (Robert Davies) writes:
>Newmat07
>
>I have released a new version of my matrix package in C++.
>
[stuff deleted]
>
The C++ Matrix class is available via anonymous ftp from `ftp.cs.ucla.edu'.
Get the compressed tarfile `pub/Matrix.tar.Z'.  Uncompress `Matrix.tar.Z'.
Extract the `Matrix' directory from `Matrix.tar'.  Then go to the `Matrix'
directory and type `make'.  Now print and read the paper in `Matrix.dvi'.

In order to demonstrate an application of the \verb"Matrix" class,
it was used to implement the backward error propagation algorithm
for multi-layer, feed-forward artificial neural networks.

Enjoy, Bob Tisdale (edwin@cs.ucla.edu)

P.S.  I hope the following notes will be helpful.

unix% ftp ftp.cs.ucla.edu
Name (ftp.cs.ucla.edu:your_login_ID): anonymous
Password: your_login_ID
ftp> cd pub
ftp> binary
ftp> get Matrix.tar.Z
ftp> bye
unix% uncompress Matrix.tar.Z
unix% tar xvf Matrix.tar
unix% cd Matrix
unix% make
unix% dvips Matrix | lpr
unix% mv ffnet.new ffnet.old
unix% cat ffnet.old ffnet.S | (backprop -v > ffnet.new) >>& ffnet.err
unix% cat ffnet.new ffnet.S | evaluate | graph -m 0 | plot

Note: If you have trouble, verify that the `SYS5' variable
      in the `Matrix/src/genclass' shell script contains
      the path to the System V version of the `m4' macro
      pre-processor.
      The `fig2dev' program is part of the `transfig' package
      available via anonymous ftp from `ftp.cs.cornell.edu'.
      Get `pub/transfig/transfig.tar.Z'.
      The EPIC style file is available via anonymous ftp from
      `ymir.claremont.edu'. Get `tex/inputs/latex-contrib/epic.sty'.
      File `pub/Matrix.sun.tar.Z' includes all the files created by
      `make' on UCLA CSD Sun4 computers.  It may be useful to Sun
      computer users or those who just want to print the documentation.
Newsgroups: sci.math.num-analysis
From: rdbeckie@water.Princeton.EDU (Roger Beckie)
Subject: Re: A postscript on domain decomposition.
Summary: Domain decomposition 
Originator: news@nimaster
Organization: Princeton University
Date: Sat, 23 Jan 1993 17:36:16 GMT

Much of the work on domain decomposition has been published in the
proceedings of a series of special conferences. The first
one is  (%E = editor, %B= title of book, %I=publisher)
%E R. Glowinski
%E G. H. Golub
%E G. A. Meurant
%E J. Periaux
%B Domain decomposition methods for partial differential equations
%I SIAM
%C Philadelphia
%P 144-172
%D 1988

The third was 
%E T. F Chan
%E R. Glowinski
%E J. Periaux
%E O. B. Widlund
%B Third International symposium on domain decomposition methods for
partial differential equations
%I SIAM
%C Philadelphia
%P 224-231
%D 1990

I believe there was a fourth conference in 1992. The proceedings should
be available from SIAM.
From: roger@maths.grace.cri.nz (Roger Young)
Newsgroups: sci.math.num-analysis
Subject: FEM with SYMMETRIC but NON-POSITIVE stiffness
Date: 27 Jan 93 08:34:32
Organization: Applied Maths, Industrial Research Ltd, NZ.
Distribution: inet
NNTP-Posting-Host: kea.grace.cri.nz


I have been following the correspondence in the num-analysis
newsgroup concerning FE methods as applied to symmetric but
non-positive definite matrices.

I appear to have a similar problem with the poro-elastic 
equations. These equations are: (1) the elastic equilibrium
equations with the pressure gradient as a source term (or,
in fact, it can be convenient to work with the variation
of these equations)

	grad(j)d(stress)(ij) = grad(i)d(pressure)

(2) the pressure diffusion equation with an additional time
derivative de/dt of the elastic dilatation e = 
grad(i)(displacement)(i)

	S.d(pressure)/dt + de/dt = -grad(i)q(i)

where the storage S can be taken as constant, and q is the
Darcy velocity which is proportional to pressure gradient
q(i) prop grad(i)(pressure).

In the displacement-pressure formulation the field vector
is chosen as z = (displacement, pressure)^T. Then according
to Lewis and Roberts "The Finite Element Method in Porous 
Media Flow" (in Fundamentals of Transport Phenomena in Porous
Media, eds Bear and Corapcioglu), the finite element equations
for the coupled problem can be written in the form

	K(dz/dt) + Hz = f

where K is SYMMETRIC.

If elasticity is decoupled from pressure, then it appears that 
the reduced stiffness matrix is positive definite for displacement
and pressure individually. However, for the coupled problem
numerical analysis appears to show that K has both +ve and -ve
eigenvalues, ie is not positive definite.

My question(s) are: is this really true? How does one set about
proving (or disproving) positive-definiteness? what is the
physical significance of positive-definiteness?

Any help from readers would be appreciated...

Roger Young (roger@maths.grace.cri.nz)
From: jk87377@lehtori.cc.tut.fi (Kouhia Juhana)
Newsgroups: sci.math
Subject: Re: Undivided distaste for algebra: math's a waste
Date: 22 Jan 1993 15:25:34 +0200
Organization: Tampere University of Technology
Distribution: world
NNTP-Posting-Host: cc.tut.fi

In article <190744.12287mccarthy@washpost.com> mccarthy@washpost.com
(Colman McCarthy) writes:
>
>America's 12.5 million high shool students
[ ..deleted..]
>cumpulsory algebra *and* geometry.

Well, if the algebra and geometry is not compulsory in US high schools,
what ever they learn there? Football? Soccer? (sp?)

Even the algebra is useless later, it helps to wide the thinking
capabilities -- ability to think mathematically helps even you never
need it later.

We call all this kind of things a common (general?) knowledge.

The idea in learning uninteresting topics, is that you
practise the learning process. Later it is easier to learn own
career if you know how to learn even difficult topics.


Juhana Kouhia
Xref: sparky sci.math:18706 soc.culture.jewish:26007
From: weemba@sagi.wistar.upenn.edu (Matthew P Wiener)
Newsgroups: sci.math,soc.culture.jewish
Subject: Re: Which CAS have BA's in math?
Date: 24 Jan 93 16:31:03 GMT
Reply-To: weemba@sagi.wistar.upenn.edu (Matthew P Wiener)
Followup-To: sci.math,soc.culture.jewish
Organization: The Wistar Institute of Anatomy and Biology
In-reply-to: rivin@SAIL.Stanford.EDU (Igor Rivin)

[Soc.culture.jewish readers: this refers to the confusion generated by
 a Computer Algebra System publishing under the name Shalosh B. Ekhad.]

In article <1993Jan22.220532.3029@CSD-NewsHost.Stanford.EDU>, rivin@SAIL (Igor Rivin) writes:
>>What is the story about SBE?  The papers I've seen seem to be somewhat
>>demented in enthusiasm, a feeling reinforced by the phoney name, which
>>gives the impression (being Hebrew for 3-in-1) that the author himself
>>is a demented with enthusiasm member of the Jews for Jesus.

>The story is that the name is not any product of the Illuminati
>conspiracy, nor of the Jews for Jesus.

That's why I ask.  I only had my impressions from a distance to go on.

>				        The computer in question is an
>AT&T 3B1 model Unix PC. You figure it out.

Let's see.  3-B-1, not 3-in-1.  OK, got it.  Perhaps it's time to work
on a secret Jew for Jesus at AT&T conspiracy theory?

>					    The enthusiasm is perfectly
>understandable -- if you were a computer proving identities, you would
>be enthusiastic too.

That depends.  What if they gave me a Genuine People Personality like
Marvin instead of one of those elevators ....

"Identity! Don't talk to me about identity!"--Weemba the Paranoid Android

>		      On the other hand, suspecting that a computer is
>a member of Jews for Jesus (or demented, for that matter), is carrying
>anthropomorphism a bit far, don't you think?

Not really.  Why the _Hebrew_ for 3-in-1 instead of, say, Japanese?

>					      If, on the other hand,
>you comments were directed at Doron Zeilberber (one of the least
>demented mathematicians of my acquiantance), I view them as slanderous
>and in extremely bad taste, especially as they are obviously made
>behind the back of their subject.

The only dementia I was referring to was the style of enthusiasm.  I'm
not expecting any "TIME HAS IDENTITY" to show up from Temple.

"Temple? Are they building the third Temple?"--Weemba the Paranoid Android
-- 
-Matthew P Wiener (weemba@sagi.wistar.upenn.edu)
Newsgroups: sci.math
From: ara@zurich.ai.mit.edu (Allan Adler)
Subject: Job Discrimination
Organization: M.I.T. Artificial Intelligence Lab.
Distribution: sci
Date: Sun, 24 Jan 1993 21:53:21 GMT


Many math departments place advertisements in which they specify that
they want to hire someone having a particular nominal specialty
and that others need not apply. I would like to examine this practice
from the standpoint of job discrimination and to get other opinions
on this as well.

What one is actually paid to do is to teach. The way one knows this is
that if one does not show up for one's classes, one is immediately
terminated. If, on the other hand, one does not do one's research
or one does not do research that empowered individuals in the department
want done, one is not immediately terminated. Of course, these individuals
might make sure your contract is not renewed. This leads me to the conclusion
that concerns about one's research fall under the category of "office 
politics", not under the category of job description.

In the former Soviet Union, the Party infiltrated all aspects of the
government and the economy and caused them to function in a different
way than they might otherwise have done. It is the same with the dominant
research specialties in a department.

I am not saying that the only legitimate function of a department is
teaching. I am saying that on paper, that is the way it is constituted
and it only behaves differently from that through this process of
office politics, which invites abuse. I feel that whatever affects
one's ability to retain one's job ought to be made explicit in one's
contract, this being part of the job description that every worker
is entitled to. If no one is willing to pay for the job description
that is currently achieved through office politics, then that is the
issue that should be confronted and taken up with the authorities that
keep things the way they are.

Now consider the following hypothetical situation, intended to test the
limits of what people consider fair in the matter of job discrimination
on the basis of specialty: imagine a university  U, which has openings
for regular math faculty but advertises that it will only hire people whose
specialities are on a certain list L of specialties, L being referred to
as the "interests of the department". Imagine that U also hires part timers, 
usually assumed to be in every way inferior to the regular faculty.
Now let M be  a mathematician whose nominal specialty, to the
extent that it can be defined at all, is not on the list L.
According to its policy, U cannot hire M as regular faculty.
However, it is willing to hire M as part time faculty, which
pays an order of magnitude less than so-called full-time work
for the same work. Now suppose that M, by virtue of skills in
areas not on the list L, is able to do better some things that
the mathematicians at U are trying but unable to do by virtue 
of having prided themselves on not knowing these areas.

Does the inferior status of M constitute job discrimination
and is such discrimination consistent with the standards of
the profession. (I am aware that it is probably legal).

Allan Adler
ara@altdorf.ai.mit.edu
From: torkel@sics.se (Torkel Franzen)
Newsgroups: sci.math
Subject: Re: Non-Standard Analysis and philosophy
Date: 21 Jan 93 21:35:08 GMT
	<1993Jan21.203027.27202@ulrik.uio.no>
Organization: Swedish Institute of Computer Science, Kista

In article <1993Jan21.203027.27202@ulrik.uio.no> solan@smaug.uio.no 
(Svein Olav G. Nyberg) writes:

   >Surely finitist mathematicians will not
   >allow for infinitely large integers.

  Your question then was not about the possibility of the existing
field of non-standard analysis, but whether a version of non-standard
analysis has been developed within constructive mathematics.
Newsgroups: sci.math,rec.arts.books,sci.philosophy.meta