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+## Copyright (C) 1995, 1996  Kurt Hornik
+## 
+## This program 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.
+## 
+## This program 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 this file.  If not, write to the Free Software Foundation,
+## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+## usage:  [errorcode, y_1, ...] = common_size (x_1, ...)
+##
+## Determine if all input arguments are either scalar or of common
+## size.  In this case, errorcode is zero, and y_i is a matrix of the
+## common size with all entries equal to x_i if this is a scalar or
+## x_i otherwise.
+##
+## If the inputs cannot be brought to a common size, errorcode is 1, and
+## y_i is x_i.
+##
+## For example,
+##
+##   [errorcode, a, b] = common_size ([1 2; 3 4], 5)
+##
+## returns errorcode = 0, a = [1 2, 3 4], b = [5 5; 5 5].
+##
+## This is useful for implementing functions where arguments can either
+## be scalars or of common size.
+
+## Author: KH <Kurt.Hornik@ci.tuwien.ac.at>
+## Created: 15 October 1994
+## Adapted-By: jwe
+
+function [errorcode, ...] = common_size (...)
+  
+  if (nargin < 2)
+    error ("common_size: only makes sense if nargin >= 2");
+  endif
+
+  va_start ();
+  for k = 1 : nargin
+    s(k, :) = size (va_arg ());
+  endfor
+  
+  m = max (s);
+  if (any (any ((s != 1)') & any ((s != ones (nargin, 1) * m)')))
+    errorcode = 1;
+    va_start ();
+    for k = 1 : nargin
+      vr_val (va_arg ());
+    endfor
+  else
+    errorcode = 0;
+    va_start ();
+    for k = 1 : nargin
+      if (prod (s(k, :)) == 1)
+	vr_val (va_arg () * ones (m));
+      else
+	vr_val (va_arg ());
+      endif
+    endfor
+  endif
+
+endfunction