SIMCON 4.5

CSGnet Archive CSG2002
1

[From Bill Powers (2002.07.02.2031 MDT)]

Success. If you don't have Dag's PCT CD-ROM, get it. Simcon 4.5 is in

Forssell - 1995 disks and threads/SIMCON

There is a complete writeup including a definition for each kind of
computing block, descriptions of all program directives, and a tutorial on
writing, running, and plotting SIMCON simulations. This is the version in
which a Simcon program consists of a file of ASCII lines that follow a
specific format.

The only thing lacking is the source code, unfortunately. Any programmer
should be able to implement all of the features of the program except one:
the algorithm for automatically figuring the order of precedence in blocks
that are "grouped", an operation that makes all the computations within a
single group execute in one iteration (rather than each block in a series
passing its output to the next during one iteration). Wolfgang Zocher
worked out this algorithm and I don't know how it works. The algorithm
isn't absolutely essential -- the programs will run without it, but there
can be subtle untruths in the results. Nothing to worry about in simple
programs.

I will continue to search for the source code of Simcon 4.5 (it's in ANSI
C), If anyone else has it stashed somewhere on an old disk, now is the time
to resurrect it. The main reason for needing the source is to see how
Wolfgang optimized the grouping. I'm pretty hazy on how he got the thing to
work with GNUPLOT, too.

Bill Williams, could there be a version of Simcon on your laptop in the
directory \TC?

I strongly advise reading simcon.txt, especially the section explaining
grouping, which also explains how Simcon acts as a parallel computer, all
computing blocks executing simultaneously (in effect).

It will become clear after you've read this document that Simcon is a
simulator for low-order systems. Giving it the power to simulate
higher-order control will be a considerable challenge -- in fact you could
say that this task defines the problems for the next century of development
of PCT.

I think we will have fun at the meeting discussing the specifications in
the document and adding whatever new ones seem reasonable for the near
future. One thing that occurs to me is that we'll want to organize any
additions so the existing system can be treated as a lower level, with the
higher systems superimposed. Like the alligator ridden by the horse ridden
by the monkey, although of course with 11 levels or so instead of only 3.

I guess that signatures don't work with the cheap (free) version
of Eudora. So here it is -- I don't plan to go on repeating the quote very
long -- anything you see too many times gets tiresome, and typing it is
even more so.

Best,

Bill P.

"Pay no attention to that man behind the curtain"
The Wizard of Oz
Best,

Bill P.

"Pay no attention to that man behind the curtain."
The Wizard Of Oz

2

[From Bill Williams 2 July 02 23:30 CST ]

Bill Powers:

Bill Williams, could there be a version of Simcon on your laptop in the
directory \TC?

The sourcecode C files seem to be in the \TC directory. Attempting to open
them gets the error message too big to fit in memory. I'll email the c
source or whatever else you need.

I just acquired for free a copy of Walter W. Soroka's 1954 _Analog Methods in
Computation and Simulation_ New York: McGraw-Hill. Lots of interesting stuff.

Bill Williams

···

______________________________________________________________________
Do you want a free e-mail for life ? Get it at http://www.email.ro/

3

[From Rick Marken (2002.07.03.0850)]

Bill Powers (2002.07.02.2031 MDT)--

Success. If you don't have Dag's PCT CD-ROM, get it. Simcon 4.5 is in
Forssell - 1995 disks and threads/SIMCON

So I guess we're abandoning the ideal of a modeling language that is
platform independent?

"Pay no attention to that man behind the curtain"
The Wizard of Oz

Great quote. As you know, I thought you would use the "A man convinced
against his will is of the same opinion still" quote for your sig, but
this is even better. It reminds me, however, of the fact that the "The
Wizard of Oz", one of the greatest movies ever made, I think, also
contains one of the most puzzling quotes of all time. The Wizard's last
words to the Scarecrow (better known as Ray Bolger) are: "And remember,
my sentimental friend, that it is not how much you love but how much you
are loved by others." I always thought this was a misreading of his
lines by the fellow who played the Wizard (damn, I forgot his name;
Frank Morgan?) and they didn't want to waste time on another take. But
a few years ago I saw a book with the original screenplay of "Wizard of
Oz" and, sure enough, that's the line as written.

Best regards

Rick

···

---
Richard S. Marken, Ph.D.
The RAND Corporation
PO Box 2138
1700 Main Street
Santa Monica, CA 90407-2138
Tel: 310-393-0411 x7971
Fax: 310-451-7018
E-mail: rmarken@rand.org

4

[From Bill Powers (2002.07.03.1007 MDT)]

Bill Williams ( 2 July 02 23:30 CST ) --
>The sourcecode C files seem to be in the \TC directory. Attempting to open

them gets the error message too big to fit in memory. I'll email the c
source or whatever else you need.

Thanks, but after writing that I found the source code for Simcon 4.5, and
have been able to compile it with Turbo C and run it. This is the last
version before 5.0. Version 5.0 was the first try at using a graphics
interface, and wasn't working right yet.

The code for 4.5 has switches in it for using Turbo C or, I think, ANSI C.
It works with Turbo C correctly -- I just had to remove a few double
definitions. Anyone using it with other machines might be able to get it
going in Unix or other C languages, maybe even Visual C++ (but that's
beyond me). This is very efficient and sophisticated code by a master
programmer which is many stages beyond the original version I started with,
and should be referred to under its author's name. That's Wolfgang Zocher.
I think we should also change the name to SimPCT because that's what
Wolfgang wanted to call it. The copyright notice on 4.5 is for 1992 -- it's
been a long time.

If we adopt this approach I think the CSG should pay its author an
honorarium for the hundreds of hours of work he has put in on it.

There's one small problem which is the graphics. Right now it uses Borland
graphics, which is OK unless you want to go to VESA or SuperVGA. There are
packages that will probably work but I don't have them running yet in C.

If anyone wants the package as it is, just tell me and I'll send it as a
zipped attachment, including the executable version and some examples.

I just acquired for free a copy of Walter W. Soroka's 1954 _Analog Methods in
Computation and Simulation_ New York: McGraw-Hill. Lots of interesting
stuff.

That's one of the books that's been on my shelt for about 45 years. The
other main book is Korn and Korn on analog computing.

Korn, G and Korn, T. _Electronic Analog Computing_, New York: McGraw-Hill 1952.

That one is inscribed with my address: 5412 S. Ridgewood Court, Chicago,
which is where Mary and I lived for the first two years of our marriage
starting in 1956. I think the only other person in our group who ever saw
that place was Kirk Sattley. Kirk, I still have the file with the molded
and baked plastic handle put on it by Bob Delgado in the kitchen of that
apartment.

Korn and Korn begins with an introduction to modeling that is excellent
reading for beginners , as well as a discussion of operational amplifiers
and how they work -- with vacuum tubes, of course, but the principles
remain the same. Granino and Theresa Korn are still alive and working with
analog computer simulations.

See http://www.modelingandsimulation.org/MayNFNetworks.html

This will show you that modeling and simulation, as well as Korn & Korn,
are very much alive, and also that we simpler souls need simpler approaches.

Best,

Bill P.

Best,

Bill P.

"Pay no attention to that man behind the curtain."
The Wizard Of Oz

5

Martin Taylor [2002.07.20 14:17]

[From Bill Powers (2002.07.02.2031 MDT)]

Success. If you don't have Dag's PCT CD-ROM, get it. Simcon 4.5 is in

Forssell - 1995 disks and threads/SIMCON

The only thing lacking is the source code, unfortunately.

I'm attaching a zip file of a folder containing the Simcon 5.2 source
code. In case that doesn't work, I've also uploaded it for anonymous
ftp at <ftp://ftp.mmtaylor.net/pub/simcon52.source.zip&gt;

Sorry it's so late--and maybe someone has already made it available
anyway. But sometimes, better late than never:-)

Martin

simcon52.source.zip (99.2 KB)

6

[From Bill Powers (2002.07.20.1359 MDT)]

Martin Taylor [2002.07.20 14:17

>I'm attaching a zip file of a folder containing the Simcon 5.2 source

code. In case that doesn't work, I've also uploaded it for anonymous
ftp at <ftp://ftp.mmtaylor.net/pub/simcon52.source.zip&gt;

Thanks, Martin. I had found most of the files, but not quite all. This
should do it.

Best,

Bill P.