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Re: Octave/Simulink question
Re: Octave/Simulink question
Wed, 26 Apr 1995 18:20:54 +0200
A few weeks ago someone mentioned freely availble program which is
to simulink what octave is to matlab. Can anyone remind me of its
name (and ftp site), please ?
Some time ago I mentioned Gnans on this list, which is probably what
you refer to. It is not a Simulab clone. You can't, for example,
assemble block diagrams with graphical user interface, but have to
write the model description yourself in an equation-oriented
language. Instead, it is believed to have other strong points. (It is
possible to write such a graphical front end though, but no-one has
volunteered!) If there is sufficient interest, it would probably be
possible to persuade me to write some nice Gnans-Octave interface.
The following announcement provides some general blurb about the
program, including ftp address. (It is also available through my WWW
home page.) (For some reason, our ftp server doesn't like the `ls'
command with parameters (like `ls -l'), which is a problem I will fix
soon. Don't be alarmed.)
Announcing Gnans version 1.3.
Gnans is a program (and language) for the numerical study of
deterministic and stochastic dynamical systems. The dynamical systems
may evolve in continuous or discrete time.
Gnans loads a system, a definition of a dynamical system in a
special, equation oriented language. The description consists of
declarations of states etc, and equations describing the dynamics of the
system. As an advanced feature, arbitrary C++-code may also be contained
in the system description. Gnans sorts the equations, translates them
into C++, which is subsequently compiled and linked into the running
program. It is then able to solve the system equations numerically with
the speed of a compiled (as opposite to interpreted) program. Several
numerical integrators, also for stochastic differential equations, are
provided. Gnans has an intuitive user interface, making it possible
control the program and to change all relevant parameters using an
intuitive point-and-click interface. In this operation, it can be
considered ``an initial value problem (IVP) engine''. Using a simple
script language, this IVP-engine can be programmed. As a by-product,
this offers the possibility of a command line interface. (Actually, as
another by-product, Gnans contains a rather powerful pocket calculator!)
Simple interactive two-dimensional plot routines are provided.
Gnans is copyrighted, but freely distributable under the Gnu
General Public License.
An C++ compiler is required, even if you just get the binaries.
The present release is only known to compile with gcc 2.6.0.
The new version has been ported to Suns with operating system SunOS
4.1.x and SunOS 5.x ("Solaris 2"), and SGI with the operating system
IRIX 5.x. There are many bug fixes, portability fixes, and internal
improvements. Relatively little has been added in functionality.
You can get Gnans by anonymous ftp to ftp.mathematik.uni-Bremen.de
(184.108.40.206 for those of you without name server). (User name
``ftp'', use your e-mail address as password.) (Our ftp-connection can
be very slow, please have patience. We will get a much faster line
"real soon now".) Binaries for Sparc (for SunOS 4.1.x) and SGI (for
IRIX 5.2) are available. Please also drop me an e-mail, and tell me
about your success with the installation, and any bugs you encounter.
Get either the source or a binary distribution. All contain full
documentation, except for some large PostScript figures, which are
only "needed" for the printed manual. The figures are available in the
file gnans-doc-pictures.tar.gz. (These are the same as included in the
1.2 distribution, so there is no need to get them again if you already
have them.) Pick up gnansdoc....ps.gz only in you cannot print the
There is a mailing group for Gnans. Please send submissions for the
mailing group to address@hidden, and requests to be
added/dropped to/from the list to address@hidden
Version 1.4 of Gnans has been released. Binaries for Sparc (Sunos
4.1.2 and Solaris 2.3), and SGI (Irix 5.2) are available. There are
no earth-scattering changes, just some bug fixes, some small new
features, bettor error messages from the translator, etc. However, the
main reason for this release is to "checkpoint my code", since I hope
to be able to do some reconstruction of the whole system in the
The popen-feature (executing scripts instead of reading them) has
changed in an incompatible fashion; you may recall that I asked the
mailing group if anyone cared for it. It turned out that what I did
not like was the syntactic overloading of opening a script; I was not
against popen-ing per se. Now it works like this: if the filename ends
with a ``|'', it is popen-ed (executed), otherwise fopen-ed
(read). Visually, it looks like a Unix pipe. (This design is stolen
I have just wrapped together the thing in quite short time, and most
likely I have made some mistakes. Please tell me about
problems when installing.
And, as usual, all sorts of feedback is very welcome.
The file gnans-doc-pictures.tar.gz has not changed, so there is no
need to get it again.
Bengt Martensson +49 421 218-2952 (office)
Institute for Dynamical Systems +49 421 17 17 13 (home)
University of Bremen +49 421 218-4235 (fax)
P.O. Box 330 440, D-28334 Bremen, Germany address@hidden