From help-octave-request at bevo dot che dot wisc dot edu  Tue Dec  8 15:20:21 1998
Subject: Announce: beta release of OCST-2.0
From: "A. Scottedward Hodel" <scotte at eng dot auburn dot edu>
To: help-octave at bevo dot che dot wisc dot edu
Date: Tue, 08 Dec 1998 15:18:16 -0600

In order to avoid future trouble, I've rewritten the Octave Control Systems Toolbox
(OCST) to store signal names as lists of strings instead of string matrices.
A beta-release of the new version is at
    ftp://ftp.eng.auburn.edu/pub/hodel/ocst-2.0.0.1.tar.gz
and has not yet been incorporated into the "bleeding-edge" Octave releases.
I'd appreciate feedback on this beta release from those who have the time
and inclination to check it out.

I've tested the code with DEMOcontrol.m (the OCST demonstration program), which
is a decent but incomplete test suite.

Documentation: Currently only in the modified DEMOcontrol script (see esp.
   system representation and block diagram manipulation).  Will soon also be
   in control.texi
New features: 
  - all signal names (states, inputs, outputs) are represented
    as lists of strings.  Lists were added to Octave in version 2.1.10.
  - Additional functions added to OCST so that system data structure manipulation
   is more "object-oriented"
   - sysdimensions: modifid to return all or individual system dimensions:
        [nc,nd,mm,pp] = sysdimensions(sys);
        mm = sysdimension(sys,"in");
   - sysgetsignals: get all signal names, some signal names, or 1 signal name.
       [stnames,innames,outnames] = sysgetsignals(sys);
       stnames = sysgetsignals(sys,"st");
       stname_4 = sysgetsignals(sys,"st",4);    # returns a list with state name 4 as its
                                                # single entry
       stname_4 = sysgetsignals(sys,"st",4,1):  # returns the string of state name 4
   - syssetsignals: change signal names (individually or as a group)
   - is_signal_list: returns nonzero if input parameter is a legal
                     list of signal names.
Incompatibilities with prior versions:  While I tried to make function calls 
  backward compatible, m-files that directly access the system data structure
  may not work.  For example:
  *** n_outputs = rows(sys.outname);
    => Since signal names are lists, rows(sys.outname) returns -1.
       instead of the above, use any of the following.

       [n_c_states,n_d_states,n_inputs,n_outputs] = sysdimensions(sys);
       n_outputs = sysdimensions(sys,"out");
       n_outputs = length(sysgetsignals(sys,"out"));

  *** sys.stname(3,1:5) = "VOLT5"
    => It is not advised to directly access the system data structure.
    => Further, lists can only take one subscript.  Instead of the above, use
       sys = syssetsignals(sys,"st",5,"VOLT5");

  I do not expect incompatibilities if users stick with the object-oriented
  functions (see sysrepdemo.m, bddemo.m).  Beta testing is to check whether or
  not I'm right.

A S Hodel Assoc. Prof. Dept Elect Eng, Auburn Univ,AL  36849-5201
On leave at NASA Marshall Space Flight Center (256) 544-1426
http://www.eng.auburn.edu/~scotte