HDTenEightyP/NetNews huggingface dataset:
From: glenn@physics.su.OZ.AU (Glenn Geers)
Subject: Finite Difference Odditity
Followup-To: Poster
Keywords:  finite difference
Organization: School of Physics, University of Sydney, Australia
Date: Tue, 28 Jul 1992 06:03:34 GMT

Hi,
   I am attempting to solve the electromagnetic vector wave equation in an 
optical fibre using a finite difference technique. The problem reduces to
an eigenvalue problem with analytic representation thus:

1-d^2/dy^2   d^2/dxdy           -id/dx           e_x

d^2/dxdy     1-d^2/dx^2         -id/dy           e_y  = W^2 n^2 E

-id/dx         -id/dy     -(d^2/dx^2 + d^2/dy^2) e_z


Where on the LHS I have explicitly shown the field components. n^2 is the
inhomogenous, lossy, anisotropic permitivity distribution.

These equations are then scaled using a non-linear scaling functions:
x = f(rho), y = g(xi) where, in general, f and g are the same.
I map all of the real plane onto the square (-.5, .5) x (-.5,.5).

I then make numerical replacements for all the derivatives leading to a 
large sparse algebraic eigenvalue problem. It turns out that the eigenvalues
I need are 1/3 of the way up from the bottom of the spectrum (this is not
a problem - I can successfully pull out eigenvalues).

The problem is as follows: On any mesh that includes the origin (even mesh) the 
eigenfunctions I obtain have ripples at the mesh period on them. On any
mesh that doesn't include the origin (odd mesh) there is no ripple on the
eigenfunctions. Any tests I do indicate that the differential operator has
been discretized correctly (e.g. supply known functions, apply operator and
compare with known analytic result). Can anyone think of a test that
will home in on this problem? seen it before? Anything?

Email is preferable because I'll probably  have to supply more detail.

Thanks in advance,
	Glenn

--
___________________________________________________________________________
Glenn Geers                       | "So when it's over, 
                                  |  we're back to people.
Department of Theoretical Physics |  Just to prove that human touch
The University of Sydney          |  can have no equal."
Sydney NSW 2006 Australia         |  - Basia Trzetrzelewska, 'Prime Time TV'
                                  |
Phone: +61 2 692-3241 (voice)     |_________________________________________
       +61 2 660-2903 (fax)       |
                                  |
glenn@physics.su.oz.au            | #include <standard_disclaimer.h>
                                  |
----------------------------------------------------------------------------
From: ara@zurich.ai.mit.edu (Allan Adler)
Newsgroups: sci.math.num-analysis
Subject: Re: Maximize Volume of Boxes in Shipping Container
Date: 24 Jul 92 22:43:19 GMT
Organization: M.I.T. Artificial Intelligence Lab.


 About 12 years ago, I helped my sister with a problem like this, only
it was a matter of maximizing the weight. I didn't need a computer and
didn't have one. Just by simple fiddling, I was able to figure
out how to get just 5 grams under an allowable limit of 20 tonnes. This
also took into account how they would all physically fit in the container.

Unfortunately, a mathematical solution to this apparently mathematical
problem overlooks some practical difficulties: (1) if the people who actually
have to do the work of packing the stuff into the container have to learn
something special or complicated in order to load the stuff into the container
according to the optimal solution, it is not going to happen. (2) The
specifications of the boxes, both their sizes and weights, are subject to
variations, often because of variations in their manufacture, sometimes
because of stupid reasons such as moisture absorbed by the cardboard.
(3) If the variations, which are not known, or the failure of the workers to
conform to the actual solution, cause one to exceed the constraints
of the problem (in your case, the dimensions of the container, in my sister's
case, the allowed weight), then that is a serious problem (in your case, it
won't fit, in my sister's case, there would be a fine).

The difficulty of taking into account variations in the parameters of the 
problem or constraints in the work practices of the people who load the 
container, when no one has ever bothered to collect that information, seems 
to argue against seeking a mathematical solution of the problem. Instead,
it seems like a better idea to tinker together a solution which is 
somewhat less than optimal and simply to ask someone in authority in the 
company  if that solution is good enough for their purposes. If they insist 
on pushing the limits of the problem, explain you can deliver better
solutions if necessary, but you need detailed information about the
factors I mentioned above.

Allan Adler
ara@altdorf.ai.mit.edu
Newsgroups: sci.math.num-analysis
From: aaronb@suhana.analog.ingr.com (Aaron B.)
Subject: Algorithm to find which bits set.
Keywords: Bit counting
Reply-To: aaronb@suhana.analog.ingr.com
Organization: Home Office Enterprise
Date: Sun, 26 Jul 1992 01:30:41 GMT

Hi there:

My friend asked me the fastest way of finding which bits are
set in a bit-string.  I gave him my first response.  But I think there
is a better way of doing it.

If anybody have a better way of doing this please E-mail me your response.

Thanks in advance.

Aaron Bustamam

aaronb@suhana.analog.ingr.com

Here is my response:

static unsigned char binvalue[9]={0x00, 0x01, 0x02, 0x04, 0x08,
                                        0x10, 0x20, 0x40, 0x80 };


/*      Main function that will take any byte and display the bits position 
	turn on.  off is the offset of the byte in the bit-string.
*/


int
show_msb(ch, off)
unsigned char ch;
long          off;
{
  int pos;

  if ( ch )
   {
     pos = ilog2( ch );
     printf("position = %d\n",pos+off);
     ch ^= binvalue[pos];         /* could also use: ch -= binvalue[pos]; */
     show_msb(ch, off);           /* recursive call for rest of bits */
   }
  return( 0 );
}

int
ilog2(n)
register unsigned char n;
{
   register long q;

   q = 0;
   while( n )
    {
      n >>= 1;
      q++;
    }
   return( q );
}   /* ilog2 */
From: wayne@econ.yale.edu (Kevin Wayne)
Newsgroups: sci.math.num-analysis
Subject: FTP Site for EISPACK / LINPACK Math Libraries
Date: 28 Jul 92 17:17:03 GMT
Organization: Economics Department, Yale University, New Haven, Ct.


Does anyone know of an FTP site that has the source code
(preferably in C) for the EISPACK or LINPACK libraries?

Please send e-mail to wayne@aida.econ.yale.edu

Thanks in advance.
Newsgroups: sci.math.num-analysis
From: n2skr@iastate.edu (Suresh K Reddy)
Subject: Phd. thesis database, (does it exist??) -an enquiry..
Organization: Iowa State University, Ames, IA
Distribution: usa
Date: Wed, 22 Jul 1992 23:01:13 GMT


 Hi,

Is there a simple way of being able to look,
at the TITLES of Phd. theses, in a particular
branch say, Electrical Engg., at some university
say, something like UIUC (University of Illinois
at Urbana Champagne)???

What I am looking for is, some archive site, at which
say I can guest login or something, and get this information,
for the last ten years maybe....

Asking for ABSTRACTS maybe too much, but TITLES atleast, I 
hope exists in database-archive...

Thanks for any help,
sury
(n2skr@iastate.edu)

p.s. I am looking for some Phd. theses related to Numerical work,
so thought this newsgroup might be appropriate..
From: flatau@lamar.ColoState.EDU (Piotr Flatau)
Newsgroups: sci.math.num-analysis
Subject: Inverse of a matrix on the basis of its eigenvalues. Is it possible ?
Date: 22 Jul 92 04:46:40 GMT
Organization: Colorado State University, Fort Collins, CO  80523

I have linear system of equations

Ax=y

and A is 10000x10000 and full (it is Toeplitz matrix). 
The conjugate gradient method I use converges in 50 iterations 
for known y. This means, I guess, that the eigenvalues are clustering ?

a) Is there a way to form an INVERSE of A from
a very limited amount of eigenvalues and eigenvectors ?
Spectral theorem ?

b) Can I get these eigenpairs from the conjugate gradient 
method ? 

c) Can I expect that 50 eigenvectors is enough to 
represent the inverse ?

Answers: "Why do you need inverse ?", "Never, ever use 
inverse when dealing with linear algebra"  do not count as correct.

Cheers, 
Peter
From: fc03@ns1.cc.lehigh.edu (Frederick W. Chapman)
Newsgroups: sci.math.num-analysis
Subject: Re: Choice of optimization methods
Date: 27 Jul 92 15:47:47 GMT
Organization: Lehigh University

In article <1992Jul27.035416.7414@u.washington.edu>,
charlie@ernie.stat.washington.edu (Charlie Geyer) writes:

>We just had a talk here last week that said that GAs had essentially no
>theory -- the "fundamental theorem" isn't even a theorem, and so forth.
>I haven't looked at the literature myself, but the speaker seemed to make
>a reasonable case.  So two questions:
>
>  1. Do GAs have any real theory?
>
>  2. Is there any problem in which GAs beat simulated annealing?
>
>-- 
>Charles Geyer
>School of Statistics
>University of Minnesota
>charlie@umnstat.stat.umn.edu


You might want to contact

     Lester Ingber (ingber@umiacs.umd.edu)
     Bruce Rosen (brosen@cis.udel.edu)

who co-authored the paper

     Genetic Algorithms and Very Fast Simulated Re-Annealing:  A Comparison

The paper asserts that

     - VFSR is statistically guaranteed to find the function optima
     - tests suggest that VFSR is orders of magnitude more efficient than GA
-- 

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
From: wayne@econ.yale.edu (Kevin Wayne)
Newsgroups: sci.math.num-analysis
Subject: Finding C Code for LINPACK/EISPACK Routines
Date: 28 Jul 92 17:11:47 GMT
Organization: Economics Department, Yale University, New Haven, Ct.



Does anyone know where I can FTP the source code (preferably in C)
to the EISPACK and LINPACK math libraries? Please send e-mail to
wayne@econ.yale.edu. Thanks in advance.
Newsgroups: sci.math.num-analysis
From: map@hal.maths.monash.edu.au (Michael Page)
Subject: Re: Math software for a mathematical pendulum of length L and mass m
Organization: Mathematics Department, Monash University, Australia
Date: Wed, 22 Jul 1992 14:18:33 GMT

In article <lexier.711772340@sfu.ca> lexier@fraser.sfu.ca (Lyle Lexier) writes:
> 
>     Is there any software for calculating the differential equation:
> 
>                    g
>          fi  =   - - sin (fi)
>            tt      L

First, it's phi not fi.  Second, this can be integrated by multiplying
both sides by phi_t, then I recall that the solution is expressible in
terms of elliptic functions.  Even without this it is pretty trivial to
integrate this numerically with 4th-order Runge Kutta for a pair of
first-order o.d.e.s 

            X_t = -g/L sin (Y) and Y_t = X.

My second-year students could do it.


--
+------------------------------------------------------------------------------+
 Michael Page, Maths Dept, Monash University, Clayton, Victoria, AUSTRALIA 3168
  email: map@hal.maths.monash.edu.au phone: +61 3 565 4486 FAX: +61 3 565 4403
+------------------------------------------------------------------------------+
From: andrew@rentec.com (Andrew Mullhaupt)
Newsgroups: sci.math.num-analysis
Subject: Re: Imaginary Numbers in C
Date: 27 Jul 92 20:30:50 GMT
Organization: Renaissance Technologies Corp., Setauket, NY.

In article <1992Jul26.162848.17382@usl.edu> pssres12@ucs.usl.edu (Vignes Gerard M) writes:
>In article <92208.174123K3006E7@ALIJKU11.BITNET> <K3006E7@ALIJKU11.BITNET> writes:
>>I am very unfamiliar with the C language, so I beg your indulgence.
>
>	If you're going to go to all that trouble,
>	you might as well do it right.

OK.
>	You can declare your own types (like complex and imaginary)
>	and then overload the conventional operators
>	+, -, *, /, to handle them easily and transparently
>	(even in combination with other numeric types).

Or just use FORTRAN where it's already all done for you. You can call FORTRAN
pretty easily from C.

>	Don't waste your time on C.

Unless the program is performance critical. In which case C++ might not
do at all.

Later,
Andrew Mullhaupt
Newsgroups: sci.math.num-analysis
From: rmz@ifi.uio.no (Bj|rn Remseth)
Subject: N dimensional FFT
Organization: Institute of Informatics, University of Oslo
Date: Fri, 31 Jul 1992 14:56:46 GMT
Originator: rmz@mellom.ifi.uio.no



Does anyone have a definition of N (where N>2) dimensional  FFT handy?
Could someone them please send one to me?


--
                                                    (Rmz)

Bj\o rn Remseth   !Institutt for Informatikk    !Net:      rmz@ifi.uio.no
Phone: +472 453466!Universitetet i Oslo, Norway !NeXTmail: rmz@neste.ifi.uio.no
Xref: sparky sci.math.num-analysis:2289 comp.lang.c++:11507
From: Dick Rinewalt <rinewalt@gamma.is.tcu.edu>
Subject: Re: Genetic Algorithms
Organization: Texas Christian Univ Comp Sci Dept
X-Useragent: Nuntius v1.1b3
Date: Fri, 31 Jul 1992 00:50:25 GMT

In article <1992Jul28.025503.1803@mnemosyne.cs.du.edu> Andrew P.Mell,
amell@nyx.cs.du.edu writes:
>I'm very interested in the subject of Genetic Algorithms, could someone
>point me towards an introductory paper on the subject, and perhaps
>(if I'm lucky!) some C code....?

Genetic Algorithms in Search, Optimization and Machine Learning, David E.
Goldberg, Addison-Wesley, 1989. [good intro and survey of past research] 

Handbook of Genetic Algorithms, Lawrence Davis (ed), Van Nostrand
Reinhold, 1991. [As the title suggests, this is more specific than
Goldberg's book. It has instructions for ordering a genetic algorithm
package.]
From: zkdc05@trc.amoco.com (Kelly D. Crawford)
Newsgroups: sci.math.num-analysis
Subject: Re: Maximize Volume of Boxes in Shipping Container
Date: 30 Jul 92 14:59:58 GMT
Organization: Amoco Production Company, Tulsa Research
Originator: zkdc05@church


> BTW, I was trying to apply genetic algorithms to this problem but lacked a
> good mutation and cross-over technique to prevent boxs (or squares in the 2D
> case) from falling outside the boundaries.  Without this you end up wasting
> most of the time on impossible combinations (unless you don't mind boxes
> slopping over the side of the truck :-)

You might try the following paper:

Smith, Derek.  "Bin Packing with Adaptive Search", First International Conference
on Genetic Algorithms and their Applications, John J. Grefenstette, editor,
Lawrence Erlbaum Associates, New Jersey, 1985.

The proceedings is still available from Lawrence Erlbaum.

Kelly
-- 
Kelly D. Crawford             | Amoco Production Research | These are my own
kcrawford@trc.amoco.com       | 4502 East 41st Street     | opinions, not
phone: (918) 660-4043         | Tulsa, OK  74102          | Amoco's...
          >>> *** This line intentionally left blank *** <<<
Newsgroups: sci.math.num-analysis
From: jonathan@chpc.utexas.edu (Jonathan Thornburg)
Subject: Re: References on High Precision Transcendentals
Followup-To: jonathan@einstein.ph.utexas.edu (Jonathan Thornburg)
Summary: a symbolic algebra system can help
Keywords: trancendental function compute approximate coefficient Maple symbolic algebra
Organization: U of Texas at Austin / Physics Dept / Center for Relativity
Date: Wed, 29 Jul 92 22:10:36 GMT

In article <81mmk2.tjm@netcom.com> tjm@netcom.com (Thomas J. Merritt) writes:
>I would like to be able to calculate sin/cos/... with ~60 digits of
>precision using a floating point format that has a 224 bit mantissa.
>
>I'm looking for references on how to calculate the coefficients that
>would be needed for the polynomial approximations.  Cody and Waite
>provide a greate discussion on how to write standard functions but only
>list a limited set of coefficients none of which are helpful.
>Computer Approximations by Hart, Et. Al., probably has enough theory in
>it to derive things.  The tables that they provide would be great but,
>agian, they do not provide the requiste precision for a 224 bit
>mantissa.  I would much prefer a more applied discussion rather than
>a theoretical one.

Hart et al describe algorithms (I believe it's "Remez' 2nd algorithm"
but I'm a little fuzzy on that) to *compute* from "first principles"
the coefficients for approximations of *any* desired accuracy.  To do
this you need (only) high-precision arithmetic and reference values,
both of which can probably be had most easily from your local symbolic
algebra system.  For example:


Script started on Wed Jul 29 17:02:10 1992
% maple
    |\^/|      MAPLE V
._|\|   |/|_.  Copyright (c) 1981-1990 by the University of Waterloo.
 \  MAPLE  /   All rights reserved.  MAPLE is a registered trademark of
 <____ ____>   Waterloo Maple Software.
      |        Type ? for help.
> Digits := 60;

                                  Digits := 60

> cos(1.0);

         .540302305868139717400936607442976603732310420617922227670097

> 4.0 * arctan(1.0);

         3.14159265358979323846264338327950288419716939937510582097494

> quit();
bytes used=161648, alloc=196572, time=.400
% exit
% 
script done on Wed Jul 29 17:04:11 1992


- Jonathan Thornburg
  <jonathan@einstein.ph.utexas.edu> or <jonathan@hermes.chpc.utexas.edu>
  University of Texas at Austin / Physics Dept / Center for Relativity
  and (for a few more months) U of British Columbia / {Astronomy,Physics}
From: dodd@mycenae.cchem (Lawrence R. Dodd)
Newsgroups: sci.math.num-analysis
Subject: Re: Surface Area and Volume Approximation
Date: 31 Jul 92 00:28:15 GMT
Reply-To: dodd@mycenae.cchem.berkeley.edu
Distribution: inet
Organization: Dept of Chemical Engineering, UC Berkeley, CA, USA
NNTP-Posting-Host: mycenae.cchem.berkeley.edu
In-reply-to: Dick Rinewalt's message of Fri, 31 Jul 1992 01:17:31 GMT


>>>>> On Fri, 31 Jul 1992 01:17:31 GMT, Dick Rinewalt
>>>>> <rinewalt@gamma.is.tcu.edu> said:

  Dick> Given a list of sphere descriptors (radius and coordinates of the
  Dick> center), I need to calculate the surface area and volume of the "shrink
  Dick> wrap" which encloses them. The structure is generally a branching one
  Dick> instead of being compact.

  Dick> If this poorly described problem sounds even vaguely familiar, I would
  Dick> appreciate any pointers to the literature.

  Dick> Dick Rinewalt             Computer Science Dept              Texas
  Dick> Christian Univ
  Dick> rinewalt@gamma.is.tcu.edu



Reference

 "Analytical treatment of the volume and surface area of molecules
 formed by an arbitrary collection of unequal spheres intersected by
 planes"

 L.R. Dodd and D.N. Theodorou
 MOLECULAR PHYSICS, Volume 72, Number 6, 20 April 1991, 1313-1345.

 FORTRAN CODE AVAILABLE
From: zkdc05@trc.amoco.com (Kelly D. Crawford)
Newsgroups: sci.math.num-analysis
Subject: Re: REQUEST : Simulated Annealing versus Genetic Algorithms
Date: 30 Jul 92 15:21:18 GMT
Organization: Amoco Production Company, Tulsa Research
Originator: zkdc05@church


In article <Bs4pAH.2AI@research.canon.oz.au>, enzo@research.canon.oz.au (Enzo Liguori) writes:
> Does anybody know about any serious study about performances of Simulated
> Annealing (SA) compared to Genetics Algorithms (GA) ?
> Personal opinions and experience are welcome as well.
> I know that there's a book called "Simulated annealing and Genetic Algorithms"
> or something like that but I've never had any chance to read it.
> I have some experience with SA, but none with GA and the only person I know who
> tryed both is extremely pessimistic about GA.
> If there's any interest I'll summarize.
> Thanks in advance.

The book you are referring to is "Genetic Algorithms and Simulated Annealing",
edited by Lawrence Davis, published by Pitman.  I don't know how much comparison
between the two will be in there, but I do know that it is a collection of papers on
the two topics (most of which [all of which?] focus on one technique or the other).

GAs are more robust than SAs, there has been much more research done on GAs,
and there is much more software available for GAs (The robustness comment is from
a GA conference held this week.  The research and software comments are my own
observations after looking at the literature.)  Although I haven't actually coded and run
an SA, I have ran several GAs with much success.  I wouldn't call myself "extremely
pessimistic" about SAs, but I *know* GAs work well from my own experience (and others
experience as evidenced from the GA literature and personal communication).

Kelly
-- 
Kelly D. Crawford             | Amoco Production Research | These are my own
kcrawford@trc.amoco.com       | 4502 East 41st Street     | opinions, not
phone: (918) 660-4043         | Tulsa, OK  74102          | Amoco's...
          >>> *** This line intentionally left blank *** <<<
Newsgroups: sci.math.num-analysis
From: Herman.Woltring@bbs.oit.unc.edu (Herman Woltring)
Subject: Re: Wanted: Hilbert transform source code
Summary: Rabiner & Gold (1975) book
Organization: Extended Bulletin Board Service
Date: Fri, 31 Jul 1992 01:36:10 GMT

In article <1992Jul30.164132.1@zodiac.dsto.oz.au> st_waldman@zodiac.dsto.oz.au
writes:
>I am looking for a Hilbert transform routine to enable me to compute
>the phase response from a magnitude-only frequency response function.
>It should be able to deal with bandpass response functions, such as
>those obtained from electrical filters and loudspeakers. I also wish
>to apply it to determine phase information from impedance magnitude
>response data. Any source code would be appreciated. I can handle
>Pascal or Fortran, and C can also be used. 
>
>Thank you...
>
>Witold Waldman
>ST_WALDMAN@ZODIAC.DSTO.GOV.AU

The FORTRAN source code for a general bandpass/differentiating/Hilbert
transform FIR filter can be found in Lawrence R. Rabiner & Bernard Gold
(1975), Theory and Application of Digital Signal Processing, Prentice-
Hall, Englewood Cliffs, NJ, USA, pp. 187-204.  I seem to recall that the
IEEE brought out a tape/diskette some years ago with DSP s/w, but I don't
have any details handy.  You might check with the IEEE Transactions on
ASSP.

Herman J. Woltring
Eindhoven, The Netherlands
Please reply to woltring@nici.kun.nl or woltring@hnykun53.bitnet, not to
the bbs address.
--
   The opinions expressed are not necessarily those of the University of
     North Carolina at Chapel Hill, the Campus Office for Information
        Technology, or the Experimental Bulletin Board Service.
           internet:  bbs.oit.unc.edu or 152.2.22.80
From: tjm@netcom.com (Thomas J. Merritt)
Newsgroups: sci.math.num-analysis
Subject: References on High Precision Transcendentals
Date: 28 Jul 92 17:55:18 GMT
Organization: Code Generation Technology

I would like to be able to calculate sin/cos/... with ~60 digits of
precision using a floating point format that has a 224 bit mantissa.

I'm looking for references on how to calculate the coefficients that
would be needed for the polynomial approximations.  Cody and Waite
provide a greate discussion on how to write standard functions but only
list a limited set of coefficients none of which are helpful.
Computer Approximations by Hart, Et. Al., probably has enough theory in
it to derive things.  The tables that they provide would be great but,
agian, they do not provide the requiste precision for a 224 bit
mantissa.  I would much prefer a more applied discussion rather than
a theoretical one.

Any references to books or papers on the topic would be greately appreciated.
Pointers to actual code for calculating constants would invaluable.

Thomas J. Merritt
tjm@netcom.com
Newsgroups: sci.math.num-analysis
From: reimann@terminator.cc.umich.edu (Dave Reimann)
Subject: WANTED: Algorithm to fit data points to ellipse
Organization: University of Michigan
Date: Thu, 30 Jul 1992 23:56:59 GMT

I need an algorithm to fit a general ellipse to a set of data points.
By generalized ellipse, I mean one that accounts for any tilt in the
major axis wrt the x-axis.  The data is expected to have some estimation 
error, so I need to handle that.