HDTenEightyP/NetNews huggingface dataset:
From: wb@arb-phys.uni-dortmund.de (Wilhelm B. Kloke)
Subject: Re: 32-bit vs 64-bit precision ?
Organization: Institut f. Arbeitsphysiologie a.d. Uni Dortmund
Date: Thu, 19 Nov 92 07:15:05 GMT

In article <1992Nov17.115111.23520@csrd.uiuc.edu> hblim@sp1.csrd.uiuc.edu (Hock-Beng Lim) writes:
>For example, are there any numerical properties which might make an
>algorithm stable when implemented in 64-bit precision ? I heard that Monte
>Carlo techniques are more stable when implemented in 64-bit precision. Is
>that true ? What about some other such differences for other well-known
>algorithms ? The algorithms I am primarily interested in are the linear
>system solvers and the eigensolvers.
At least, it is well known that dot products which occur in Matrix
multiplication should be carried out in higher precision than that of
the stored elements. Dot products (Sum over A_i * B_i) tend to
cancellation if the vectors are nearly orthogonal. This will cause
problems if the matrices are ill-conditioned.
-- 
Dipl.-Math. Wilhelm Bernhard Kloke,
Institut fuer Arbeitsphysiologie an der Universitaet Dortmund
Ardeystrasse 67, D-4600 Dortmund 1, Tel. 0231-1084-257
Newsgroups: sci.math.num-analysis
From: hblim@sp1.csrd.uiuc.edu (Hock-Beng Lim)
Subject: 32-bit vs 64-bit precision ?
Organization: Univ of Illinois, Center for Supercomputing R&D, Urbana, IL
Date: Tue, 17 Nov 92 11:51:11 GMT

I have a question which I hope the numerical analysis gurus can help
me out. I would like to find out what are the factors to consider
when deciding whether to implement a numerical algorithm in 32-bit
or 64-bit floating-point precision, apart from the obvious difference
in their precision.

For example, are there any numerical properties which might make an
algorithm stable when implemented in 64-bit precision ? I heard that Monte
Carlo techniques are more stable when implemented in 64-bit precision. Is
that true ? What about some other such differences for other well-known
algorithms ? The algorithms I am primarily interested in are the linear
system solvers and the eigensolvers.

HB
--
---------------------------------------------------------------------
Hock-Beng Lim			Center for Supercomputing R&D
hblim@csrd.uiuc.edu		Univ. of Illinois at Urbana-Champaign
Newsgroups: sci.math.num-analysis
Subject: PDE solution algorithms?
From: cachoo@lincoln.ac.nz
Date: 20 Nov 92 15:07:19 +1300


Hello everyone:

I am looking for a public domain package to solve sytems of Partial
Differential Equations. Somewhere I read about a package called FORSIM,
which uses Runge-Kutta with variable step size. I have used this technique 
to solve Ordinary Differential Equations, but I can't quite grasp how it can be 
used for PDE's.
I have been using the finite differencing techniques described in PDE books,
but my solutions are very unstable and sensitive to grid size. I'm sure there 
are some algorithms out there that improve on this, but since i'm new to PDE's,
I'm completely confused. Any help will be appreciated. 

Thanks:
  Oscar Cacho
  Lincoln University
  Canterbury 
  NEW ZEALAND
From: jwg@sparcman.cray.com (John Gregory)
Newsgroups: sci.math.num-analysis
Subject: Re: question: how to show that a set of linear inequalities is consistent?
Date: 18 Nov 92 15:13:36 GMT
Reply-To: jwg@sparcman.cray.com (John Gregory)
Organization: Cray Research, Inc.


In article <batra.722077145@beagle>, batra@boulder.Colorado.EDU (sajeev batra) writes:
|> hi,
|> 
|> I have a large set of  linear inequalities (with about a 20 unknowns)
|> and I am about to use linear programming to solve for them.
|> Is there an algorithm that will tell me that my set is consistent or
|> inconsistent?  

Finding out whether a set of inequalities is consistent is on average
about half the work of solving the entire LP.  Unless there is some special
characteristic of your model that allows a priori analysis, there are no simple shortcuts that will give you what you want.  One proves a set is consistent
by finding a feasible solution;  one proves it's inconsistent by showing that
no feasible solution exists.  In either case an LP algorithm (probably the Simplex method) is your best bet.

|> Also, I need to know specifically which inequalities
|> contradict each other.  How do I go about doing this?  Any suggestions?

This question really is not as well-posed as you may think.  If a group
of inequalities is inconsistent (infeasible), there may be many ways of
removing a few to give a feasible set.  It's not likely you can point at
one or two and say "those are the culprits". One technique that comes to 
mind is goal-programming.  There are several ways people implement this, 
but one of the simplest is to add to each row an extra slack variable that
has a huge but meaningful cost of violating that constraint.  The model
is now feasible, since at a large cost the solver can just put in the new
slacks.  If the costs you assign are physically meaningful, then the
Simplex method will find the least costly way to violate as few constraints
as possible.

There is a recognized expert in the field of LP, Fred Glover, who is at
the University of Colorado at Boulder.  You may find it beneficial to
try to talk over your ideas with him.

- John Gregory
  Applications Dept.
  Cray Research, Inc.
Newsgroups: sci.math.num-analysis
From: trammell@antithesis.engin.umich.edu (James Trammell)
Subject: Sources found...Thanks
Date: Tue, 17 Nov 92 04:57:26 EST
Organization: The University of Michigan AI and VR Laboratory
Followup-To: sender
Originator: trammell@antithesis.engin.umich.edu


Never Mind....
From: pa@verano.sba.ca.us (Pierre Asselin)
Newsgroups: sci.math.num-analysis
Subject: Re: Gauss/Lobatto Quadrature Code
Date: 13 Nov 92 05:09:43 GMT
Organization: None.  Santa Barbara, CA

In <+kcqmdd@lynx.unm.edu> warsa@polaris.unm.edu (j warsa) writes:

-Becuase of the numerous requests for such [Gaussian quadrature] programs,
-I thought that there may not be any available in the traditional math
-library archives (like netlib, etc.)

I'm pretty sure netlib has one in the "golden oldies".
Try "send index from go".
-- 

--Pierre Asselin, Santa Barbara, California
  pa@verano.sba.ca.us
Newsgroups: sci.math.num-analysis
From: lessard@acs.ucalgary.ca (Rodney Lessard)
Subject: Re: calling Fortran libraries with C
Date: Mon, 23 Nov 92 20:13:17 GMT
Distribution: ba
Organization: The University of Calgary, Alberta
Keywords: Fortran, C

In article <1ep9qjINNsni@agate.berkeley.edu> actize@garnet.berkeley.edu () writes:
>I program in C, and most of our mathematical libraries are in Fortran 77.
>Our online documentation describes a few things, such as 
>1.	Fortran calls by address
>2.	The order of array storage is different.
>
>Does anybody have experience with this, and advice ?
>
>David
>actize@garnet.berkeley.edu

I have had some experience with this phenomena by calling NCAR
graphics and IMSL fortran routines from my C code. It is actually
not that difficult. Here some examples.

1. Fortran programs must be declared extern.
	extern int srface();
2. Like you mentioned arguments must be passed by address.
	call srface(x,y,10) looks like

	static int c_10 = 10;
	float x[100],y[100];
	srface(x,y,&c_10);
3. String arguments must be passed their length at the end of the
argument list.
	call srface(x,y,'Title') looks like

	srface(x,y,"Title",5L);
4. Ordering of multi-dimensional arrays is different. For example
	x(10)(20) would look like
	x[200] where x(1)(1..20) fills x[0..19] and so on.

This part is a little tricky and may need some test programs if
your not sure. After all is said and done maybe you should try
the f2c program available from netlib to get some idea of how it
is done. Note: you will have to do some tricks to get common
block declarations going. Basically you declare a structure.
E-mail me if you need more help.

Cheers






-- 
| Rod Lessard					lessard@acs.ucalgary.ca      |
| Cosmic Ray Group				2500 University Drive	     |
| Dept. of Physics and Astronomy		Calgary, AB, Canada	     |
| University of Calgary				(403) 220 - 3640	     |
Newsgroups: sci.math.num-analysis
From: hudson@ux1.cso.uiuc.edu (John Hudson)
Subject: Need curve fitting routine for ampl. _and_ phase
Summary:  of n-harmonic cos wave
Organization: University of Illinois at Urbana-Champaign
Date: Mon, 16 Nov 1992 15:42:12 GMT

I need curve fitting routine (or even an algorithm that is
known to work) that will fit data to a 2 or 3 harmonic 
cosine wave with the amplitude and phase of each harmonic.

I would rather use a routine that is written specifically for
this case than apply a general nonlinear fitter.

Thanks in advance,

John Hudson

Newsgroups: sci.math.num-analysis
From: batra@boulder.Colorado.EDU (sajeev batra)
Subject: Re: netlib (another question)
Keywords: X interface
Organization: University of Colorado, Boulder
Date: 18 Nov 92 07:09:56 GMT

hi,

i have another question about netlib.  I've never used it before and am
having some trouble accessing files.  I do have the instructions but
they seem a little ambiguous.

I want to download the linear programming package "lp".  what should
my command be?  I have been trying "send lp".  I've also tried
"send index from lp ".  And I've tried accessing an alternative
linear prog package "ampl/models".   But, no luck!  Any suggestions?

Thanks.

sajeev.
batra@cs.colorado.edu
From: pa@verano.sba.ca.us (Pierre Asselin)
Newsgroups: sci.math.num-analysis
Subject: Re: contour plot
Date: 21 Nov 92 06:09:14 GMT
Organization: None.  Santa Barbara, CA

In <14737.2b0bf3a9@ohstpy.mps.ohio-state.edu>
	luk@ohstpy.mps.ohio-state.edu writes:

>I am looking for a routine for contour plot, given discrete numerical data 
>f(x,y) on a rectangular region.  Can anyone help

Algorithm 626, by Albrecht Preusser,  ACM Transactions on Mathematical
Software, v.10, no.4, p. 473 (1984).  In Fortran.  Routine tricp takes 3
arrays x,y,z and plots the contours of z vs. x,y.  Calls the Calcomp
routines plots and plot(x,y,ipen); it's easy to supply your own and
intercept the generated pen strokes.

Source available from netlib.  "send 626 from toms".  Have fun.
-- 

--Pierre Asselin, Santa Barbara, California
  pa@verano.sba.ca.us
From: marcouil@ireq.hydro.qc.ca (Luc Marcouiller)
Subject: Re: ftp site or anything else for Gaussian evaluation of integrals
Reply-To: marcouil@ireq.hydro.qc.ca
Organization: Hydro-Quebec
Date: Thu, 19 Nov 1992 16:16:22 GMT

The numerical receipes package (in fortran at least) has a subroutine which
will calculate those abcisses and weight for any interval and any number of
points.  I don't remember the name of the routine but it's described in the
accompanying book in the numerical integration section. My 0.02$

---------------------------------------------------------------------------
   Luc Marcouiller,                  Institut de Recherche d'Hydro-Quebec,
   Chercheur                         1800 Montee Ste-Julie, Varennes,
   Service Mecanique                 P. Quebec, Canada, J3X 1S1
                                     Tel: 514-652-8152 Fax: 514-652-8309
   Repondre a: /  Reply to: -------> marcouil@ireq.hydro.qc.ca
Newsgroups: sci.math.num-analysis
From: ac@mentor.cc.purdue.edu (ac)
Subject: XDataSlice and HDF Library
Organization: Purdue University Computing Center
Distribution: usa
Date: Wed, 18 Nov 1992 02:53:56 GMT


	I'm looking for XDataSlice and HDF Library, both were develped
by National Center for Supercomputing Applications at U. of Illnois at
Urbana. I heard that they are available in public domains. Where are 
they?

	Any sguuestion is highly appreciated!!


Alex Chou
EE, Purdue U.
shihtsun@ecn.purdue.edu
ac@mentor.cc.purdue.edu
From: mld900@anusf.anu.edu.au (Murray Dow)
Newsgroups: sci.math.num-analysis
Subject: constrained minimum
Date: 18 Nov 1992 00:26:33 GMT
Organization: ANU Supercomputer Facility
Distribution: world
Reply-To: mld900@anusf.anu.edu.au
NNTP-Posting-Host: 150.203.5.3
Keywords: nonlinear, minimum, constrained
Originator: mld900@asterix


Someone was recently asking for a program to solve a multivariable
non-linear minimization problem. I sent of my old program but
I don't think you got it? Is any one interested? 
As I said, the methods of Gill and Murray using sequential
quadratic programming are superior but their program is not
public domian. (It is in NAG)

-- 
Murray Dow                         GPO Box 4 Canberra ACT 2601 Australia
Supercomputer Facility             Phone: +61 6 2495028
Australian National University     Fax:   +61 6 2473425
mld900@anusf.anu.edu.au
Newsgroups: sci.math.num-analysis
From: zika@gn.ecn.purdue.edu (Michael Zika)
Subject: Re: contour plot
Organization: Purdue University Engineering Computer Network
Date: Fri, 20 Nov 92 04:21:39 GMT

In article <14737.2b0bf3a9@ohstpy.mps.ohio-state.edu> luk@ohstpy.mps.ohio-state.edu writes:
>I am looking for a routine for contour plot, given discrete numerical
>data f(x,y) on a rectangular region.  Can anyone help

I have been pleased with the NCAR routines.  Although the "meta" file
it writes was a bit hard to get used to at first, the fitting
routines worked well for my rectangular-grid application.

Dunno if these are publicly available -- anyone know where or how to
get a hold of these?

>luk


-- 
                                     |
Michael Zika (zika@ecn.purdue.edu)   |    Hey don't ask me "why?",
Purdue University                    |    I'm still working on "how?" ! 
School of Nuclear Engineering        |
Newsgroups: sci.math.num-analysis
From: ekronent@lonestar.utsa.edu (Eric I. Kronenthal)
Subject: ftp site for numerical recipes in FORTRAN
Organization: University of Texas at San Antonio
Date: Wed, 18 Nov 1992 04:34:20 GMT

I am very new to this group, so excuse me if this is an inappropriate question.

Is there an FTP site for the source included in the book
"Numerical Recipes for FORTRAN"

Email me at ekronent@lonestar.utsa.edu
or post if this is concern to many

Eric Kronenthal

-- 
Eric Kronenthal
Graduate Information Systems
University of Texas (San Antonio)
Internet: ekronent@lonestar.utsa.edu
Xref: sparky sci.math:15351 sci.lang:8149
From: ara@zurich.ai.mit.edu (Allan Adler)
Newsgroups: sci.math,sci.lang
Subject: daisu = algebra
Date: 21 Nov 92 22:42:28 GMT
Distribution: sci
Organization: M.I.T. Artificial Intelligence Lab.



I'm trying to see whether my pathetic efforts to teach myself Japanese
over the last few years will enable me to read a mathematics book in
Japanese.

I've noticed that the character SU comes up often in mathematical terminology.
For example, DAISU means algebra and KEISU means coefficient. So I would
like to know of all the mathematical terminology one can think of that
involves this character. Please send me a list. I will make similar requests
as time goes on.

I am also somewhat puzzled as to the etymology of DAISU, as meaning algebra,
and of similar words. By looking at the individual characters, it looks
like DAISU literally means "rules for substitution", but I'm probably off
by a mile. So part of the question is to explain why these terms involving
SU mean what they mean.

Apart from that, if someone would like to volunteer to answer by email other 
unbelievably naive questions about Japanese by email, please let me know.

Allan Adler
ara@altdorf.ai.mit.edu
Newsgroups: sci.math
From: fernee@newton.physics.uq.oz.au (Mark Fernee)
Subject: Help! Order dependent complex integration
Organization: Physics Dept. The University of Queensland
Date: Tue, 17 Nov 1992 08:32:20 GMT

I have come across a double integral of the following form;


      /  /         -iwt   -iz(t-tau)
     |  |  dw dz  e      e
     |  |        -----------------
     |  |        (w+a)(z+b)(w+z+c)
    /  /

Both integrals are to be evaluated along the real axis from
minus infinity to infinity. The terms a,b and c are complex 
constants with Im(a), Im(b) and Im(c) > i0 and Im(a) and Im(b)
>> Im(c). Also t and tau are real and > 0 with t-tau > 0.

I have attempted to evaluate the integral using Cauchy's
residue theorem by completing a contour around the poles
for each successive integral, using the sign of the exponent
in the numerator to determine around which half of the complex
plane to close the integral. 

The problem is that the solution is dependent on the order of
integration. I have as yet found no means to justifiably order
the integration.

The solutions that I get, differ by a sign and are as follows;

w integration followed by z integration:

           / iat  ib(t-tau)      ict  i(a-c)tau \
        2 | e    e          +   e    e           |
    -4pi  | ____________________________________ |
          |              (c-a-b)                 | 
           \                                    /

z integration followed by w integration:


           / iat  ib(t-tau)      ict  i(a-c)tau \
        2 | e    e          -   e    e           |
    -4pi  | ____________________________________ |
          |              (c-a-b)                 | 
           \                                    /


If you could spot my mistake, or offer a solution, please 
E-mail me. 

Thanks,

Mark.

Newsgroups: sci.math
From: ruberman@binah.cc.brandeis.edu
Subject: Re: A Question About Fundamental Group
Reply-To: ruberman@binah.cc.brandeis.edu
Organization: Brandeis University
Date: Wed, 18 Nov 1992 20:20:07 GMT

In article <amirishs.722059588@acf9>, amirishs@acf9.nyu.edu (shaahin amiri sharifi) writes:
>Consider a bunch of infinitely many (countable) circles with a
>point in common. The radii of these circles make a sequence like
>{1/n}. What is the fundamental group of this space? Any comments
>or referenc would be so helpful!

You have to be a little careful about what topology you're using on this
space.  I assume, from your description,  that you're talking about
this set as lying in a plane, with the subspace topology.  Then the
fundamental group has been computed; there is a paper (within the last
few years) by John Morgan, although I  don't remember the precise reference.
(There was apparently an earlier, incorrect computation by someone else).
In any event, the fundamental group is not a free group, as would be the
case for a finite union of circles, or the infinite union topologized
eg as a CW complex.
Newsgroups: sci.math
From: west@symcom.math.uiuc.edu (Douglas West)
Subject: Re: Counting Families of Subsets
Organization: University of Illinois at Urbana
Date: Sat, 21 Nov 1992 22:08:50 GMT

kinnersley@kuhub.cc.ukans.edu (Bill Kinnersley) writes:

>Take a base set S with N elements.  There are 2^N subsets of S.
>I want to consider families of these subsets.  All together there
>are 2^{2^N} such families, but I want to impose a condition.

>Let F be a family such that all elements of F are distinct subsets,
>and no element of F is a subset of another.

The log base 2 is asymptotic to n choose n/2.
See D.J. Kleitman and G. Markowsky, On Dedekind's problem: the number of
monotone Boolean functions II, Transactions AMS 45(1974), 373-389.
From: fogel@rosarita.berkeley.edu (Micah E. Fogel)
Newsgroups: sci.math
Subject: Another fundamental group question
Date: 18 Nov 92 23:28:16 GMT
Organization: U.C. Berkeley Math. Department.
NNTP-Posting-Host: rosarita.berkeley.edu


	I once saw in this newsgroup an article describing a space that was
supposed to have fundamental group equal to some non-discrete group (I think
it was the reals, but the rationals is also possible).  Or was I just dreaming?

					Micah Fogel
					fogel@math.berkeley.edu
Newsgroups: sci.math
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: Most important event in the history of mathematics
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Fri, 20 Nov 92 21:36:36 GMT

Ben Fok ("the Lemming") writes: "How about the discovery of Chaos and
Fractals?"  Let's hope that this is a joke... since perhaps it *is* the
most important event for the lemmings among us.
Organization: Johannes Kepler University Linz - Computing Center
Date: Thursday, 19 Nov 1992 12:56:53 CET
From: Mutter Christoph Johannes <K3032E2@ALIJKU11.BITNET>
Newsgroups: sci.math
Subject:    sumhar math a

RDRLIST
Newsgroups: sci.math
From: wft@math.canterbury.ac.nz (Bill Taylor)
Subject: Counterfactuals.
Organization: Department of Mathematics, University of Canterbury
Date: Tue, 24 Nov 1992 03:39:46 GMT

The recent discussion about whether P=NP made me wonder.....

There are quite a number of theorems beginning, "if P =|= NP then..."; and
presumably masses beginning "if P = NP then..." .

In a different area, number theory, there are a great many theorems beginning
"if Riemann's hypothesis is true then...",  and presumably one or two beginning
"if Riemann's hypothesis is false then...." .

So what happens to these results of the "wrong" sort, when and if the 
conditioning result is decided.  Do they suddenly become uninteresting ? Do
they suddenly lose all their information content, or do they still retain
some ?

( Perhaps they should be solemnly excised from all copies ofjournals, like
the Stalinesque instructions to encyclopaedia owners when a politician
suddenly fell from favor...... ).

Well, it's a pretty vague question; but perhaps someone can think of a pretty
vague but sensible answer ?

------------------------------------------------------------------------------
              Bill Taylor              wft@math.canterbury.ac.nz
------------------------------------------------------------------------------
                   There's no future in living in the past. 
------------------------------------------------------------------------------
Xref: sparky sci.math:15009 sci.physics:18927
From: sl3nf@cc.usu.edu
Newsgroups: sci.math,sci.physics
Subject: Re: Three-sided coin
Date: 15 Nov 92 17:20:21 MDT
Organization: Utah State University

In article <jim.721702281@st-michael>, jim@cs.UAlberta.CA (Jim Easton) writes:
> gmortens@rodan.acs.syr.edu (Gerald E Mortensen) writes:
> 
>>>>>> von Neumann was asked, when about to enter a taxi,
>>>>>>
>>>>>>"How thick should a coin be to have equal (=1/3) probability
>>>>>> of landing on its head,tail,or edge?"
> 
> If you make these assumptions then it works out that the ratio of
> diameter to thickness is sqrt(3).  However I don't think assumption
> 2 is realistic - If the coin is tossed on a table it bounces around
> quite a bit before it settles.
> 
> Given that it is possible to bounce from one state to another it
> is more probable to bounce out of a high energy state to a lower
> energy state than it is the reverse.  I claim that the lowest energy
> state is the most probable and therefore conclude that the three states
> should be equal in energy.
> 
> That implies that the thickness is equal to the diameter.
>
	Unfortunately, this problem is one with an infinite number of possible
answers.  Both the sqrt(3) ratio, and the equal energy states (where the h/2 =
radius) are essentially correct.
	If you were to toss the coin from a height of zero (or another 
extremely low height), then the first idea is correct, because bounce dynamics
has very little or no effect.  On the other hand, if your height is not
negligible, then the final possible energy states must be equal.
	Since it is very difficult to drop a coin from a zero altitude, I'd
have to say the second is *more* correct, even though both ideas have thier

 "... where the 'stuff of life' is raining out of the skies..." 
                                -Carl Sagan 
                         sniggerfardimungus
                        in%"sl3nf@cc.usu.edu"
                 The usual disclaimers apply anywhere 
                     you can find a sticky spot.
 

is correct, because bounce
Newsgroups: sci.math