## 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: cond (a)
##
## Return the condition number of a, computed using the singular values
## of a.
##
## See also: norm, svd

## Author: jwe

function retval = cond (a)

  if (nargin == 1)
    [nr, nc] = size (a);
    if (nr == 0 && nc == 0)
      if (! propagate_empty_matrices)
        error ("cond: empty matrix is invalid as argument");
      endif
      if (strcmp (propagate_empty_matrices, "warn"))
        warning ("cond: argument is empty matrix\n");
      endif
      retval = 0.0;
    endif
    sigma = svd (a);
    retval = sigma (1) / sigma (length (sigma));
  else
    usage ("cond (a)");
  endif

endfunction