### Copyright (C) 1996 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, 59 Temple Place - Suite 330, Boston, MA
### 02111-1307, USA.

## Usage: is_symmetric (x {,tol})
##
## If x is symmetric, return the dimension of x, otherwise, return 0.
##
## See also: size, rows, columns, length, is_matrix, is_scalar, 
## is_square, is_vector

## Author: A. S. Hodel <scotte@eng.auburn.edu>
## Created: August 1993
## Adapted-By: jwe

function retval = is_symmetric (x,tol)

  if (nargin == 1 || nargin == 2)
    if ((retval = is_square (x)))
      if (nargin == 1)
	tol = eps;
      endif
      if (norm (x - x') / norm(x) > tol)
        retval = 0;
      endif
    endif
  else
    usage ("is_symmetric (x {,tol})");
  endif

endfunction