**Today's Topics:**

- NA News Policy on Long Conference Announcements
- Solution of Linear Congruence Equations
- Stability for Initial-Boundary Value Problems
- Scientific Computing/Computational Math/Numerical Science
- Linpack-like routines in C
- Continued Support for PRC Students/Researchers on NSF

From: Eric Grosse (and Cleve Moler) <ehg@research.att.com>

Date: Mon, 12 Jun 89 21:05:46 EDT

As was suggested in last week's Digest, let's put long conference

announcements in NETLIB. Since we're archiving the NA-Digest to the

dawn of time, the switch won't even increase disk use. :-)

Authors should choose a 14-character or less alphanumeric

conference title, say NAConFab89, and include the hint

mail netlib@research.att.com

send NAConFab89 from meetings

in their brief announcement in the NA-Digest. They should mail

the long form to ehg@research.att.com with

Subject: deposit meetings/NAConFab89

If the name collides with an existing file, the new announcement

will be appended to the existing one.

Best wishes

Eric

------------------------------

From: Giuseppe Paruolo <AGG0%ICINECA.BITNET@Forsythe.Stanford.EDU>

Date: Mon, 12 Jun 89 11:47:08 ITA

Given the linear congruence equation

a x = b mod m (*)

we know that (*) does have solution if and only if gcd(a,m) divides b.

In this situation:

1) is it possible to solve (*) analitically?

(I think the answer is no, but I'd like confirmation anyway)

If the answer to 1) is no as I suppose:

2) what are the existing algorithms to solve this problem?

which of them is the most efficient?

3) what are the concrete problems, the real applications in which

equations like (*) have to be solved, and where their solution

affects heavily the computational complexity and/or the

storage requirement?

Bibliographical references on this problem and suggestions are welcome.

Thank you in advance.

Giuseppe Paruolo

address: Giuseppe Paruolo - CINECA - via Magnanelli 6/3

40033 Casalecchio - Bologna - Italy

e-mail: agg0@icineca.bitnet or na.paruolo@na-net.stanford.edu

fax: + 39 51 598 472

------------------------------

From: Rakesh <rakesh@vax1.acs.udel.edu>

Date: Mon, 12 Jun 89 10:14:44 EDT

I am looking for articles which have reasonable sufficient conditions for

the stability of difference schemes, for initial_boundary value problems for

the wave equation in 2 space dimensions i.e.

u - u - u + q(x,y)u = F(x,y,t) x>0, y in R , t>0

tt xx yy

IC u(x,y,0) = 0, u (x,y,0) = 0

t

BC u(0,y,t) = f(y,t) { or u (0,y,t) = f(y,t) }

x

I am aware of the work on first order systems, but when I convert the above

equation to a first order system it fails to satisfy the "non-characteristic"

condition needed for the results for systems. Perhaps, I am overlooking

something.

I would appreciate any help on this matter. Thanks.

rakesh@vax1.acs.udel.edu (on arpanet)

(302) 451 2910

------------------------------

From: Benedict Leimkuhler <bleimkuh@uunet.uu.net>

Date: 15 Jun 89 09:05:54 GMT

I am interested in what the opinions of others are on the meanings

of the terms "Scientific Computing," "Computational Mathematics," and

"Numerical Science."

Recently, these terms have become buzzwords in position announcements

and popular science articles. For example, Stanford has recently created

a "Program in Computational Mathematics and Scientific Computing." In

an article in the latest issue of The Economist which focused

on large scale simulation of physical phenomena on supercomputers, the

above three terms are stated to be synonyms. I expect to see a large

number of new positions created in the next few years with one of

those terms in the title, and I'm rather curious about whether or not

I'm in one of these fields.

To add to the confusion, Bill Gear, in his farewell address as SIAM

president, discusses the importance in the coming years of something

called "Computing Science."

I have always sort of considered myself to be a "Numerical Analyst."

Now I know that the people who run supercomputer centers use some terms

like "Supercomputing" or "Supercomputing Science," and if they

work on graphical output from supercomputers they call it "Visualization

Science." The parallel processing community has nothing against the

term "Parallel Computing," as far as I know, since they and everyone

else seems to use the term in titles and abstracts all the time.

If you have any ideas or more terms to throw into this alphabet soup

send me EMAIL and I will post a summary to the net.

Ben Leimkuhler

(Numerical Analyst?)

Helsinki University of Technology, Finland

------------------------------

From: Daniel Q. Naiman <jhunix!msc_wdqn@purdue.edu>

Date: 16 Jun 89 06:55:14 GMT

Does anyone out there know of alternatives to Linpack written in the C

language and for which the source code is in the public domain. It is

important that it have various matrix inversion programs, especially for

banded matrices. Also, it is important that the programs be written with

numerical issues taken seriously.

Please post or send mail to

Dan Naiman

(msc_wdqn.jhunix)

The Johns Hopkins University - HCF

------------------------------

From: National Science Foundation <jrom@note.nsf.gov>

Date: Thu, 15 Jun 89 17:36:11 -0400

The following letter was signed today by Erich Bloch, Director,

NSF, to announce the availability of supplementary funds to

continue support for those students and researchers from the

People's Republic of China whose tenure in the United States will

be altered. As with other supplement requests, these should be

sent to the NSF Program Officer who was designated as the

cognizant program official when the research award was made.

Dear Colleague:

Last week, in response to events in the People's Republic of

China (PRC), President Bush offered a one-year delayed departure

to all PRC students, scholars and other visitors now in the

United States.

Many visitors from the PRC currently receive support through NSF

awards, particularly as graduate students and postdoctoral

researchers. Effective immediately, NSF will entertain requests

for supplements if the duration of the stay of a PRC student or

other researcher supported on an existing award is altered as the

result of the President's initiative.

Requests for supplements under this provision should be in the

form of a brief letter, signed by both the principal investigator

and the institutional official, and submitted directly to the

appropriate NSF Program Official. The letter should state

clearly that this is a supplemental request to provide continued

support for a PRC student or researcher. The individual(s)

involved should be identified and the circumstances of the case

outlined in sufficient detail for the NSF Program Manager to

evaluate the request.

NSF staff will make every attempt to expedite the processing of

these requests and provide notification of award to the

institutions promptly.

Erich Bloch

Director

------------------------------

End of NA Digest

**************************

-------