is_siso.m

similer program for matlab

## Copyright (C) 1996, 2000, 2002, 2003, 2004, 2005, 2006, 2007
##               Auburn University.  All rights reserved.
##
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## -*- texinfo -*-
## @deftypefn {Function File} {} is_siso (@var{sys})
## Returns nonzero if the system data structure
## @var{sys} is single-input, single-output.
## @end deftypefn

## Author: A. S. Hodel <[e-mail]>
## Created: July 1996, 1998

function  SISO = is_siso (sys)

  if (nargin != 1)
    print_usage ();
  elseif (! isstruct (sys))
    error ("input must be a system structure (see ss, tf, zp)");
  endif

  [n, nz, m, p] = sysdimensions (sys);

  SISO = (m == 1 && p == 1);

endfunction