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Volume: 6, Issue: 9, Tue Dec  6 09:26:45 EST 1988

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| TODAY'S TOPICS |
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(1) Protein Modeling at JvNC
(2) Random Numbers

* Moderator: Paul Fishwick, Univ. of Florida
* Send topical mail to: simulation@uflorida.cis.ufl.edu
* Archives available via FTP to bikini.cis.ufl.edu, login as
  'anonymous', use your last name as the password, change
  directory to pub/simdigest.



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Date:         Thu, 01 Dec 88 15:16:31 EST
From: David Salzman <SALZMAN@pucc.princeton.edu>
Subject:      Protein Modeling at JvNC, Dec. 5 (Please Post
To: comp-simulation@rutgers.edu


                        Richard Feldmann
                 National Institutes of Health

       The Role of Intuition in The Modeling of Proteins

                   Monday, December 5, 1988
       4:00 PM (Refreshments will be served at 3:40 PM)


Physical intuition about molecular models can be formalized as
sophisticated computer models, but the converse is not
necessarily true.  Experience has shown that computer models with
visual representations yield more physical insight than models
with purely numerical output, but the exact form of the visual
representation matters further.  Feldmann will present protein
models in a variety of media--stereoscopic, motion picture,
tactile, etc.--as illustrations of the principle.  Stereo
glasses will be provided.

Richard Feldmann has been involved with issues of presenting
macromolecular structure since he joined the National Institutes
of Health in 1967.  He now works in the NIH's Division of
Computer Research and Technology.  He received his degrees from
the University of Dayton and the Polytechnic Institute of New
York.

Talks are free and open to the public.  The John von Neumann
National Supercomputer Center (JvNC) is supported by the National
Science Foundation and the New Jersey Commission on Science and
Technology.  Talks are held at 665 College Road East, Princeton
Forrestal Center, Plainsboro NJ.  For further information, call
(609)520-2000.



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Date:    30 Nov 88 14:21:02 GMT (Wednesday)
To: simulation%uflorida.cis.ufl.edu@NSS.CS.UCL.AC.UK
From: Peter Dickman <pwd%computer-lab.cambridge.ac.uk@NSS.CS.UCL.AC.UK>
Subject: Random Numbers

George Bier points to the recent CACM article by Stephen Park & Keith Miller
on 'multiplicative linear congruence' pseudo-random number generators and
asks whether anyone knows of any theory which allows for the fact that these
algorithms generate numbers without replacement.

In Knuth Vol. 2, 2nd Edition (pp 26 -- 28) an additive generator devised by
Mitchell & Moore is described. It is efficient (no multiplies, it requires
an addition MOD (2^n) & two pointer decrements plus possibly a resetting of
a pointer if it hits zero) and has a period of (2^f)(2^55 - 1) for some f:
0 <= f < n. Knuth says that the theory behind the generator is not well-known
though & proofs of good randomness are lacking.

The generator does require a little more state than the MLC approaches though
and is still working without replacement (if one views all 55 words of state
plus the two pointers as all combining together to describe the current random
number - when their values are all precisely repeated the sequence will start
again). Anyway, while people are thinking about the lack of replacement, does
anyone know if the randomness of this generator has been investigated?
In particular how does it compare with the 'minimal standard generator'
proposed in the CACM article (Vol 31 No 10 pp 1192 -- 1201)?

Disclaimer: I'm not a theorist, I just want a good pseudo-random number supply.

Thanks,
      Peter

ARPA: pwd@cl.cam.ac.uk
UUCP: {Atlantic Ocean}!mcvax!ukc!cam-cl!pwd



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