Static-gain SS calls

[Luther Tychonievich]

To whom it may concern,

Matlab controls toolbox syntax permits calls to ss(D) as well as ss(A,B,C), ss(A,B,C,D), etc. This can be added to octave's with a fairly trivial change; in .../octave/2.9.9/m/control/system/ss.m, replace the current if statement starting on line 193 with the following two if blocks:

  ## Test for correct number of inputs
  if ((nargin == 2) | (nargin > 11))
    usage("retsys = ss  (a,b,c{,d,tsam,n,nz,stname,inname,outname,outlist})\nusage: retsys = ss  (d)");
  endif


  ## If only one parameter is supplied, it is D; all others are empty
  if (nargin == 1)
    d = a; 
    a = zeros(0,0); 
    b = zeros(0,columns(d)); 
    c = zeros(rows(d),0);
  endif


Presumably some note of this should be added to the documentation, too.

Luther Tychonievich