## Copyright (C) 1995, 1996  Kurt Hornik
##
## 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, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
## 02110-1301, USA.

## -*- texinfo -*-
## @deftypefn {Function File} {[@var{err}, @var{y1}, ...] =} common_size (@var{x1}, ...)
## Determine if all input arguments are either scalar or of common
## size.  If so, @var{err} is zero, and @var{yi} is a matrix of the
## common size with all entries equal to @var{xi} if this is a scalar or
## @var{xi} otherwise.  If the inputs cannot be brought to a common size,
## errorcode is 1, and @var{yi} is @var{xi}.  For example,
##
## @example
## @group
## [errorcode, a, b] = common_size ([1 2; 3 4], 5)
##      @result{} errorcode = 0
##      @result{} a = [ 1, 2; 3, 4 ]
##      @result{} b = [ 5, 5; 5, 5 ]
## @end group
## @end example
##
## @noindent
## This is useful for implementing functions where arguments can either
## be scalars or of common size.
## @end deftypefn

## Author: KH <Kurt.Hornik@ci.tuwien.ac.at>
## Created: 15 October 1994
## Adapted-By: jwe

function [errorcode, varargout] = common_size (varargin)

  if (nargin < 2)
    error ("common_size: only makes sense if nargin >= 2");
  endif

  len = 2;
  for i = 1 : nargin
    sz =  size (varargin{i});
    if (length (sz) < len)
      s(i,:) = [sz, ones(1,len - length(sz))];
    else
      if (length (sz) > len)
	if (i > 1)
	  s = [s, ones(size(s,1), length(sz) - len)];
	endif
	len = length (sz);
      endif
      s(i,:) = sz;
    endif
  endfor

  m = max (s);
  if (any (any ((s != 1)') & any ((s != ones (nargin, 1) * m)')))
    errorcode = 1;
    varargout = varargin;
  else
    errorcode = 0;
    for i = 1 : nargin
      varargout{i} = varargin{i};
      if (prod (s(i,:)) == 1)
	varargout{i} *= ones (m);
      endif
    endfor
  endif

endfunction