# Copyright (C) 1996 A. Scottedward Hodel 
#
# This file is part of Octave. 
#
# Octave is free software; you can redistribute it and/or modify it 
# under the terms of the GNU General Public License as published by the 
# Free Software Foundation; either version 2, or (at your option) any 
# later version. 
# 
# Octave is distributed in the hope that it will be useful, but WITHOUT 
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 
# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License 
# for more details.
# 
# You should have received a copy of the GNU General Public License 
# along with Octave; see the file COPYING.  If not, write to the Free 
# Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. 
 
function retsys = syschtsa(sys,tsam)
#
# retsys = syschtsa(sys,tsam);
#
# This function changes the sampling time (tsam) of the system.

# Written by John Ingram August 1996

  if (nargin != 2)
    usage("retsys = syschtsa(sys,tsam)");
  elseif (!is_struct(sys))
    error("sys must be in system data structure form");
  elseif(!is_scal(tsam))
    disp("syschtsa:")
    tsam
    error("tsam must be a scalar")
  elseif ( ! (is_sampl(tsam) | (tsam == 0) ) )
    error("tsam must be real, scalar, and greater than zero");
  elseif (sysgetts(sys) == 0)
    [nc,nz,mm,pp] = sysdimen(sys);
    warning("syschtsa: continuous system (nc=%d, nz=%d, mm=%d, pp=%d)", ...
      nc,nz,mm,pp);
    warning("syschtsa: The system is continuous, use c2d to make the system discrete");
  endif

  retsys = sys;  
  retsys.tsam = tsam;

endfunction
