# Copyright (C) 1993 John W. Eaton
# 
# 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 x = kron (a, b)

# Usage: x = kron (a, b)
#
# Form the Kronecker product of two matrices, defined block by block
# as 
#
#   x = [a(i,j) b]

# Written by A. S. Hodel (scotte@eng.auburn.edu) August 1993.

  if (nargin == 2)

    [m, n] = size (b);
    [ma, na] = size (a);

# Do 1st column.

    x = a (1, 1) * b;
    for ii = 2:ma
      x = [x; a (ii, 1)*b];
    endfor

# Do remaining columns.

    for jj = 2:na
      tmp = a (1, jj)*b;
      for ii = 2:ma
	tmp = [tmp; a (ii, jj)*b];
      endfor
      x = [x, tmp];
    endfor

  else
    error ("usage: kron (a, b)");
  endif

endfunction