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## 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: rot90 (x, k)
##
## Rotate the matrix x counterclockwise k*90 degrees.
##
## If the second argument is omitted, k is taken to be 1.
##
## See also: flipud, fliplr
## Author: jwe
function y = rot90 (x, k)
if (nargin < 2)
k = 1;
endif
if (imag (k) != 0 || fix (k) != k)
error ("rot90: k must be an integer");
endif
if (nargin == 1 || nargin == 2)
k = rem (k, 4);
if (k < 0)
k = k + 4;
endif
if (k == 0)
y = x;
elseif (k == 1)
y = flipud (x.');
elseif (k == 2)
y = flipud (fliplr (x));
elseif (k == 3)
y = (flipud (x)).';
else
error ("rot90: internal error!");
endif
else
usage ("rot90 (x [, k])");
endif
endfunction
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