HDTenEightyP/NetNews huggingface dataset:
From: walsteyn@fys.ruu.nl (Fred Walsteijn)
Subject: Re: Comparison between FEM and FDM/CVM for fluid flow modeling
Organization: Physics Department, University of Utrecht, The Netherlands
Date: Mon, 14 Dec 1992 23:16:25 GMT

In <1992Dec14.132457.24381@dutrun2.tudelft.nl> rcpshdb@dutrun2.tudelft.nl (Han de Bruijn) writes:

>In article <1992Dec11.165920.3016@magnus.acs.ohio-state.edu> Shekhar Damle:
>> Besides the ability to model complex geometries, what are the advantages
>> of FEM over the more established Finite Difference Methods(FDM) or Control
>> Volume Methods (CVM) when it comes to fluid flow modeling ?
>None.
>> Does the situation change if fluid flow is coupled with heat transfer as
>> has to be done while modeling solidification ?
>No.
>> Is the situation different if the flow is turbulent ?
>No.

I disagree.
Galerkin methods have the advantage that without much effort
(for example quadratic) conservation properties hold in the
(semi-) discrete system too.
This is known to be important if ``viscosity is low''.
For example in 2-D turbulence usage of linear FEM methods
leads to conservation of (semi-) discrete energy and enstrophy.
That's true even for complicated domains.
(Arakawa's special FD discretization is identical to such a method
 in cartesian domains/grids but required a much more complicated derivation.)
It turns out that even in poorly resolved flows (as is usual in turbulence
simulations) the discrete energy cascade behaves much like the real thing.
A non-conserving method would produce inferior results (inaccuracies
and possibly instabilities) much earlier in the process of increasing
Reynolds number.  Nice examples can also be found in the book
of Canuta et al (Spectral methods, Springer Verlag ?) for MHD simulations.
Note that conservation is not a complete guarantee for accuracy: if the viscosity
is very low (resolution much too coarse) then discrete artefacts will show
up.  In 2-D turbulence: so-called enstrophy equipartitioning.
The remaining advantage is that in these cases the Galerkin
method is nonlinearly stable, while simple centered FD  & FV schemes would have
exploded ``yesterday''. :-)

Hmm. I hope this helps a bit...
Good luck,
Fred.
-----------------------------------------------------------------------------
Fred Walsteijn                                | Internet: walsteyn@fys.ruu.nl
Institute for Marine and Atmospheric Research | FAX:      31-30-543163
Utrecht University, The Netherlands           | Phone:    31-30-533169
Newsgroups: sci.math.num-analysis
From: muthu@mecad.uta.edu (S.N. Muthukrishnan)
Subject: Re: FEA help!
Reply-To: muthu@mecad.uta.edu
Organization: University of Texas at Arlington
Date: Wed, 16 Dec 1992 14:20:30 GMT

In article <1992Dec15.225304.11571@porthos.cc.bellcore.com>  
bhatia@bigcat.bellcore.com (Raman Bhatia) writes:
> In article <1992Dec14.181725@roper.mc.ti.com>, a722756@roper.mc.ti.com (W.  
Donald Rolph) writes:
> |> 

[Good information deleted for space]

> 
> Thanks for a very informative post. Here's another question. What are
> the latest in Mesh Generation techniques? 
> 
> The last time I dabbed in FEM, the finite-octree (w Delaunay triangulation) 
> appeared the most promising but there were some concerns about robustness. 
> I know that companies like PDA engineering (developers of PATRAN) were 
> looking at "paving". What is the current status of these two techniques, 
> and are there any new ones out there (AI approaches etc.)?
> 
> Raman Bhatia (bhatia@bigcat.bellcore.com)

Yes. The finite octree method for INITIAL mesh generation may be good. There is  
also sufficient work-in-progress in the area of Delaunay triangulation. Refer  
to Dr. Sheppard's comprehensive summary of mesh generation techniques for more  
information on mesh generation procedures. 

This is not what I want to share. FEM's success partially depends on the  
quality of the mesh used for analysis. It is imperative to possess sufficient  
knowledge about the model to adequately represent an area or domain of high  
singularity. That is where adaptive remeshing is good. Several papers published  
have proven the capability of h-p analysis methods. I believe, so far no  
commericial code carries the h-p procedure. I might be wrong! Any idea?

-Muthu 

--
---------------------------------------------------------------------
S. N. Muthukrishnan                | muthu@mecad.uta.edu |
Dept.of Mech. Engg., UT, Arlington | muthu@fem.uta.edu   |(NeXT mail)
Arlington, TX  76019               | muthu@newton.uta.edu|
_____________________________________________________________________
"Perception is a reality. Reality is myth"
---------------------------------------------------------------------
Newsgroups: sci.math.num-analysis
From: kerr@ux1.cso.uiuc.edu (Stan Kerr)
Subject: Re: MINOS
Organization: University of Illinois at Urbana
Date: Thu, 17 Dec 1992 16:53:17 GMT

bvaddi@eng.auburn.edu (Bala V. Vaddi) writes:


>Instead buy GAMS. It comes with MINOS and lots of other packages. Further it is a 4GL language, i.e. easy to use.

That may be, but the GAMS language is quite limited in the types of nonlinear
functions it can express. There are still excellent reasons for getting
MINOS independently and using good old Fortran. GAMS shines only in its
ability to make a model intelligible and maintainable.
-- 

Stan Kerr    
Computing & Communications Services Office, U of Illinois/Urbana
Phone: 217-333-5217  Email: stankerr@uiuc.edu   
Newsgroups: sci.math.num-analysis,sci.math.symbolic
From: oliveria@engin.umich.edu (Roque Donizete de Oliveira)
Subject: mail problem concerning requests about "Functional Differential Equations"
Date: Thu, 17 Dec 92 00:48:59 EST
Organization: University of Michigan Engineering, Ann Arbor

  Skip Thompson (thompson@reed.science.runet.edu) asked me to post this 
on his behalf (he doesn't have access to usenet). He wants to inform 
those who requested info about his work (fortran and TeX paper) on FDEs 
(Functional Differential Equations) with state dependent delays that he 
is having problems replying (or mailing directly). Most likely he 
has received your inquiry though. He is tracking down the mail problem now.
If he can't fix the problem today (Thursday, Dec 17 1992), he will on Friday
reply to you from his account at Oak Ridge National Lab (skip@msr.epm.ornl.gov).
You can contact him at that e-mail address as well. If the problem continues,
anyone who wishes can contact him by telephone at 703-831-5478 or 703-382-3075. 

   Roque
   oliveria@engin.umich.edu
   Nuclear Eng Dept, The U. of Michigan
Newsgroups: sci.math.num-analysis
From: rcpshdb@dutrun2.tudelft.nl (Han de Bruijn)
Subject: Re: Comparison between FEM and FDM/CVM for fluid flow modeling
Originator: rcpshdb@dutrun2.tudelft.nl
Reply-To: rcpshdb@dutrun2.tudelft.nl (Han de Bruijn)
Organization: Delft University of Technology
Date: Wed, 16 Dec 1992 09:56:23 GMT

In article <1992Dec15.092213@roper.mc.ti.com> W. Donald Rolph:
> The issue remains the shape or approximation functions. Chooses identical
> shape funcitons and FVM and FEA are identical. Choose bad ones, and both
> fail.
> Fundamentally all numerical procedures for PDE approximation have a basic
> underlying comonality: minimizing error in the approximation funcitons with
> respect to the actual solution.

Reading your postings, I can conclude that you are obviously well informed
about the Finite Element Method. But I can also conclude that you are
quite ignorant about Finite Volume and Finite Difference methods.

The idea that FD and/or FV are just a sub-class of FEA is distributed by
Zienkiewicz, Oden and others, and it has NOTHING to do with reality.

It's the same as saying that men and women are the same. They are NOT.
Due to their differences, they can have children. Due to the differences
between Finite Elements and Finite Differences / Volumes, there could be
progress in numerical methods. But when I take a look into those huge
volumes, everything appears the same as fifteen years ago ... Yaaaawn.

But at least we can _visualize_ our common numerical ignorance now,
with great graphical toolboxes like AVS.

> We realy need to get away from these parochial battles over differences
> in what are in fact identical procedures.

YES, we need to get away from these parochial battles. And NO, they are
not "in fact identical procedures". Let me not advertise again my work
on "Unified Numerical Approximations".

Selfishness is our ONLY problem, even in science & technology.
-- 
* Han de Bruijn; Applications&Graphics | "A little bit of Physics * No
* TUD Computing Centre; P.O. Box 354   | would be NO idleness in  * Oil
* 2600 AJ  Delft; The Netherlands.     | Mathematics" (HdB).      * for
* E-mail: Han.deBruijn@RC.TUDelft.NL --| Fax: +31 15 78 37 87 ----* Blood
Newsgroups: sci.math.num-analysis
From: rcpshdb@dutrun2.tudelft.nl (Han de Bruijn)
Subject: RE: Comparison between FEM and FDM/CVM for fluid flow modeling
Originator: rcpshdb@dutrun2.tudelft.nl
Reply-To: rcpshdb@dutrun2.tudelft.nl (Han de Bruijn)
Organization: Delft University of Technology
Date: Mon, 14 Dec 1992 13:24:57 GMT

In article <1992Dec11.165920.3016@magnus.acs.ohio-state.edu> Shekhar Damle:
> Besides the ability to model complex geometries, what are the advantages
> of FEM over the more established Finite Difference Methods(FDM) or Control
> Volume Methods (CVM) when it comes to fluid flow modeling ?

None.

> Does the situation change if fluid flow is coupled with heat transfer as
> has to be done while modeling solidification ?

No.

> Is the situation different if the flow is turbulent ?

No.

> The reason I raise these questions is that I do not know of any other
> advantages of FEM vis-a-vis fluid flow modeling. I do not consider myself
> to be an expert in CFD by any means and I am quite willing to change my mind.

> (Of course it goes without saying that the ability to model complex geometries
> can be quite significant in many situations)

So far so good. Are we truly willing to change our mind?

How about the idea to CHANGE both nowadays FDM and FEM methods?

In fact, nowadays FVM and FEM represent totally different _cultures_,
and it's very difficult, sometimes even dangerous, to cross over from
one champ to the other. But perhaps _that_ should represent a challenge
for everybody who is working in the field. Or are we too "pragmatic",
too busy with our "demanding applications" to consider such a thing?

SUNA = Series on Unified Numerical Approximations.

Numerical methods are not a gift from the gods. They were invented by
humans, and the same humans are free to change the boundary conditions.

SUNA articles are available now on a (more or less) permanent basis, via
"anonymous ftp". They can be retrieved as follows:

   ftp dutrde1.tudelft.nl          (: internet-adress = 130.161.180.13)
   Name:                           (: "anonymous")
   Password:                       (: <user>@<host> )
   cd pub/suna
   ls                              (: list of "suna*.net" articles)
   mget <filenames>

See also "SUNA, Published so far" for the complete list of available articles;
it is contained in the file: "sunall.net". Not everything may be of interest.
Articles may be outdated and sometimes even wrong. Start with "The Manifesto".

Gee, it's indeed high time to clean up this stuff ...
-
* Han de Bruijn; Applications&Graphics | "A little bit of Physics * No
* TUD Computing Centre; P.O. Box 354   | would be NO idleness in  * Oil
* 2600 AJ  Delft; The Netherlands.     | Mathematics" (HdB).      * for
* E-mail: Han.deBruijn@RC.TUDelft.NL --| Fax: +31 15 78 37 87 ----* Blood
From: pa@verano.sba.ca.us (Pierre Asselin)
Newsgroups: sci.math.num-analysis
Subject: Re: Numerical Integration Problem?
Date: 10 Dec 92 07:03:01 GMT
Organization: None.  Santa Barbara, CA

In <1992Dec8.163024.7472@IRO.UMontreal.CA>
	simardr@IRO.UMontreal.CA (Richard Simard) writes:

:2- notice the integral is exactly the confluent hypergeometric
:function (apart from a constant). Use the asymptotic expansion
:for large x.

Darn!  I didn't see that one.  Does netlib have anything that
Brian could pick up?
-- 

--Pierre Asselin, Santa Barbara, California
  pa@verano.sba.ca.us
Newsgroups: sci.math.num-analysis
From: robt@is.morgan.com (Rob Torop)
Subject: Band Matrix Multiplication
Keywords: Matrix Vector
Organization: Morgan Stanley - IDT
Date: Tue, 15 Dec 1992 19:54:57 GMT


I have some code, the core of which is a loop that computes the transformation of a
vector by a band matrix multiple times:

	x <-- Bx    where  B  =    b c 0 . . . 0
			           a b c . . . 0
				   . . .
		                   0 0 0 . a b c

Right now, I'm basically doing the obvious thing, looping over the vector.  I have this nagging feeling that there is something brilliant and very different that can be done.  I'm running on Sun Sparcs (2 and 10), in case that makes a difference.  Any advice?


-- Rob Torop

+---------------------------------------------------------------------+
| The views expressed here are neither mine nor those of my employer. |
+---------------------------------------------------------------------+
From: kmorriso@zeus.calpoly.edu (Kent E Morrison)
Newsgroups: sci.math.num-analysis
Subject: PD Differential Equation Solver for the Mac
Date: 19 Dec 92 22:46:22 GMT
Organization: Cal Poly State University, San Luis Obispo

Is there a public domain or shareware differential equation
solver for use in introductory differential equation courses
(for the Macintosh)? It should plot slope fields, vectorfields,
and integral curves and be usable by novices. Commercial
programs include "Differential Systems" and "MacMath". On the
PC side there is "MDEP."
Distribution: world
Organization: California Polytechnic State University, San Luis Obispo
Keywords: 


-- 
______________________________________________________________________________
Kent Morrison                           kmorriso@nike.calpoly.edu
Math Dept                               office: (805) 756-2464
Cal Poly                                dept:   (805) 756-2206
From: sshankar@td2cad.intel.com (Sadasivan Shankar)
Newsgroups: sci.math.num-analysis
Subject: Re: Nonlinear systems of equations
Date: 18 Dec 92 21:28:43 GMT
Reply-To: sshankar@td2cad.intel.com (Sadasivan Shankar)
Organization: Intel Corporation, Santa Clara, CA USA


Typically, Newton-based techniques are local continuation methods and the initial guess
is very important.  In most of the cases, I have used (highly non-linear as well) N-technique
they have converged unless you have cases like turning points, bifurcation points, and so on.
Since you already have an idea of the solution, I suspect that the problem could be due
some small error in your Jacobian.  In most of the cases, double-checking your Jacobian will
be your worthwhile.

S.Shankar
Tech CAD
INTEL Corporation
Newsgroups: sci.math.num-analysis
From: sullivan@teal.csn.org (Steve Sullivan)
Subject: Multigrid methods conf: Elsewhere, please
Organization: Colorado SuperNet, Inc.
Distribution: na
Date: Sat, 12 Dec 1992 02:32:40 GMT


Please consider moving your upcoming
multigrid methods conference to another state ...
and hopefully return to Colorado after we
overturn a highly discriminatory law.

Although you may feel that an academic conference
has no political implications, it does.

Recently Colorado narrowly passed a law which essentially
legalizes discrimination against gay and lesbian people.
Numerous cities across the country (Atlanta, New York, etc.)
have responded by banning official travel to Colorado,
and many conferences originally scheduled for Colorado
have been relocated.

While this boycott of Colorado is controversial, many of us
within Colorado see the boycott as an effective tool to
get the attention of thoseg hatred, and to eventually
overturn this unjust law.

I ask you to help support our effort for equal rights by
relocating your upcoming conference to another state.

Stephen Sullivan           sullivan@csn.org

The opinions expressed here are my own personal opinions,
and are not meant to represent the views or opinions
of any associated organization.

Newsgroups: sci.math
From: sbardhan@uncc.edu (Soumendu Bardhan)
Subject: The golden number
Reply-To: sbardhan@uncc.edu
Organization: University of NC at Charlotte
Date: Thu, 17 Dec 1992 20:20:53 GMT

Will someone start discussing about it. I'm not sure  about its properties.

Newsgroups: sci.math
From: nas_ps@geds01.jsc.nasa.gov (Pradip R. Shah)
Subject: IMSL : RBEST ROUTINE
Reply-To: nas_ps@geds01.jsc.nasa.gov
Organization: G.E. Government Services
Date: Mon, 14 Dec 1992 19:59:42 GMT

HI !!

I Have the following problem with the IMSL (International Mathematical Statistical
Library) software.   Those of you who are familiar or are currently using it, I 
would sincerely appreciate your help.

I am trying to generate a regression equation using the routine "RBEST" which selects
the best multiple linear regression analysis.  My problem is that I can not get
the intercept.  The design matrix, as I understand, should have the first column
elements equal to 1 (for constant regressor).  I am getting the singular matrix.
The illustration uses the data from the Draper & Smith and I have been working with
this data set before I can really analyze my data.  If someone can help me with
this problem, I would be grateful.

Thanks.

P.S.  My reference is IMSL : Fortran routines for Statistical Analysis, Softcover
edition 1.1, pgs. 176-182.

Pradip Shah GE
From: newsman@stein.u.washington.edu (Christian Ricci)
Newsgroups: sci.math
Subject: Matgraph
Date: 17 Dec 92 02:22:25 GMT
Article-I.D.: u.1992Dec17.022225.13296
Organization: University of Washington, Seattle

I need to aquire a copy of Matgraph for a class I'm about to take.  I'm 
wondering there is a PD graphing program that will do about the same thing.

I need to graph signals in continuous and discrete time.  I also need to 
graph signals in the frequency domain.  I'm not sure if it will need to do
Fourier transforms but that would be nice.  

I need this file to run under either MS-Dos or Windows or OS2.  I could 
install my unix and X-windows if there is a program that will require it
but I prefer not to.  

I appreciate any suggestions.  Thanks!

Chris

PS-If you know of a archive site too, I'd appreciate that information.  Thanks
again!
Newsgroups: sci.math,comp.edu,misc.education
From: wayman@lamar.ColoState.EDU (Jeffrey Wayman)
Subject: Re: Education crisis (was RE: how much math...)
Date: Sun, 13 Dec 1992 04:10:16 GMT
Organization: Colorado State University, Fort Collins, CO  80523

In article <PRENER.92Dec12015805@prener.watson.ibm.com> prener@watson.ibm.com (Dan Prener) writes:
>In article <1gac6gINNfeo@agate.berkeley.edu> bh@anarres.CS.Berkeley.EDU (Brian Harvey) writes:
>
>> hrubin@pop.stat.purdue.edu (Herman Rubin) writes:
>> > erh0362@tesla.njit.edu (Elliotte Rusty Harold) writes:
>> >>If a child wants to learn about dinosaurs, let him or her learn about 
>> >>dinosaurs.  If they want learn about football, let them learn about football.
>> >
>> >This ignores the problem of prerequisites.   The point of a curriculum is
>> >so that the background is there when it is needed.  This holds even for
>> >graduate students.
>
>> Graduate students, yes.  Little kids, no.  It makes sense that as one gets
>> older, more mature, more able to understand the delayed rewards of education,
>> one can be expected to accept a more disciplined schooling.
>
>   [ ... and more ... ]
>
>For two reasons, I arrive at the opposite conclusion.
>
> (1)  Little kids are less likely to question authority.
>
> (2)  Little kids learn much faster.
>
>For these two reasons, I think educators have not only the opportunity, but
>the obligation to use their authority to cram as much knowledge(*) into
>little kids' heads as they reasonably can.  This amounts to a blatantly
>paternalistic "Learn this now, because I say so, rather than later, when
>you realize it might be useful."  But the fact that little kids' learning
>capacity is so much greater than that of older people makes it a kindness.

How about a balance of both?  Actually, I think this was the point of
the original post.  Naturally, if we let the kids choose all that they
learn, they won't be ready for everything they need to be when they need
to be.  However, I think the method of cramming all knowledge in because
we want it in contributes to poor attitudes later on.  A child needs to 
be exposed to a certain amount of learning of his choosing so he can see
that learning can be fun.  He can then carry over these successes to 
other subjects.

>This argument is in no way specific to mathematics; it applies in many
>disciplines.  Think how appropriate it is for languages.
>
>(*)  I do not, of course, mean randomly or capriciously selected knowledge.
>     However flawed it may be, the traditional selection for little kids
>     is preferable to current fads, since one of the benefits of formal 
>     education is its conservative nature. 
>--


Jeff          wayman@lamar.colostate.edu
Newsgroups: sci.math,rec.puzzles
From: wabe@ukc.ac.uk (W.A.B.Evans)
Newsgroups: sci.math
Subject: Re: Orbital motion question
Date: 14 Dec 92 19:15:34 GMT
Reply-To: wabe@ukc.ac.uk (W.A.B.Evans)
Organization: Computing Lab, University of Kent at Canterbury, UK.

In article <1ggfesINN29q@access.usask.ca> choy@skorpio.usask.ca (I am a terminator.) writes:
>
>Let the vector r be the position of a mass m orbiting in a plane around
>another mass M (which doesn't move) at the origin. The mass m is
>accelerated such that
>
>   2
>  d r     KMm
>m --- = - ---- r
>    2        2
>  dt      |r|
>
	Do you REALLY mean an inverse FIRST Power Law or the usual inverse
SQUARE Law - in the which case you should have

   2
  d r     KMm
m --- = - ---- r
    2        3
  dt      |r|

>                                           r
>                                         d---
>                                          |r|
>What is the scalar product of r/|r| and ------ ?
>                                          dt
>
	The rate of change with time of the unit radial vector is 

      d theta
      -------  x  unit vector  theta            ( in polar co-rds r,theta)
        dt

and, so is always perpendicular to the unit radial vector. This is true 
whatever the central force - or whether your orbit is elliptic, parabolic
or hyperbolic ( inverse SQUARE force). It would also be true for other orbits
which in general would not be closed i.e. they precess.

                                          W. Alan B. Evans
                                          [ wabe@ukc.ac.uk ]
Newsgroups: sci.math
From: pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt)
Subject: Re: Function Terminology
Organization: Computer Science Department,  Stanford University.
Date: Fri, 11 Dec 1992 20:38:02 GMT

In article <1gaq3tINNg9q@uwm.edu> radcliff@csd4.csd.uwm.edu (David G Radcliffe) writes:
>Suppose I have a function f: A --> B, and C is a subset of B which
>contains the image set of f.  I define a function g: A --> C by
>setting g(a) = f(a) for all a in A.  Usually, f and g can be considered 
>as the same function, but sometimes the distinction is important.
>
>Is there a standard term or notation for this?

While I've not heard of one, one could borrow notation used to make the
analogous distinction for the integer 2 viewed as the real 2. and write
f:A->B as f. and f:A->C as just f without the point.
-- 
Vaughan Pratt				All knowledge resides in the going odds