## Copyright (C) 2004, 2005, 2006, 2007 David Bateman
##
## 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 3 of the License, 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, see
## <http://www.gnu.org/licenses/>.

## -*- texinfo -*-
## @deftypefn {Function File} {} flipdim (@var{x}, @var{dim})
## Return a copy of @var{x} flipped about the dimension @var{dim}.
## For example
##
## @example
## @group
## flipdim ([1, 2; 3, 4], 2)
##      @result{}  2  1
##          4  3
## @end group
## @end example
## @seealso{fliplr, flipud, rot90, rotdim}
## @end deftypefn

## Author: David Bateman

function y = flipdim (x, dim)

  if (nargin != 1 && nargin != 2)
    print_usage ();
  endif

  nd = ndims (x);
  sz = size (x);
  if (nargin == 1)
    ## Find the first non-singleton dimension.
    dim = 1;
    while (dim < nd + 1 && sz(dim) == 1)
      dim = dim + 1;
    endwhile
    if (dim > nd)
      dim = 1;
    endif
  else
    if (! (isscalar (dim) && dim == round (dim)) && dim > 0 && dim < (nd + 1))
      error ("flipdim: dim must be an integer and valid dimension");
    endif
  endif

  idx = cell ();
  for i = 1:nd
    idx{i} = 1:sz(i);
  endfor
  idx{dim} = sz(dim):-1:1;
  y = x(idx{:});

endfunction