update packages

[CreaPhase.git] / octave_packages / m / general / shift.m

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+## Copyright (C) 1995-2012 Kurt Hornik
+##
+## 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} {} shift (@var{x}, @var{b})
+## @deftypefnx {Function File} {} shift (@var{x}, @var{b}, @var{dim})
+## If @var{x} is a vector, perform a circular shift of length @var{b} of
+## the elements of @var{x}.
+##
+## If @var{x} is a matrix, do the same for each column of @var{x}.
+## If the optional @var{dim} argument is given, operate along this
+## dimension.
+## @end deftypefn
+
+## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at>
+## Created: 14 September 1994
+## Adapted-By: jwe
+
+function y = shift (x, b, dim)
+
+  if (nargin != 2 && nargin != 3)
+    print_usage ();
+  endif
+
+  if (numel (x) < 1)
+    error ("shift: X must not be empty");
+  elseif (! (isscalar (b) && b == fix (b)))
+    error ("shift: B must be an integer");
+  endif
+
+  nd = ndims (x);
+  sz = size (x);
+
+  if (nargin == 3)
+    if (!(isscalar (dim) && dim == fix (dim))
+        || !(1 <= dim && dim <= nd))
+      error ("shift: DIM must be an integer and a valid dimension");
+    endif
+  else
+    ## Find the first non-singleton dimension.
+    (dim = find (sz > 1, 1)) || (dim = 1);
+  endif
+
+  d = sz(dim);
+
+  idx = repmat ({':'}, nd, 1);
+  if (b > 0)
+    b = rem (b, d);
+    idx{dim} = [d-b+1:d, 1:d-b];
+  elseif (b < 0)
+    b = rem (abs (b), d);
+    idx{dim} = [b+1:d, 1:b];
+  endif
+
+  y = x(idx{:});
+
+endfunction
+
+
+%!test
+%! a = [1, 2, 3];
+%! b = [4, 5, 6];
+%! c = [7, 8, 9];
+%!
+%! r = [a, b, c];
+%! m = [a; b; c];
+%!
+%! assert(shift (r, 0), r);
+%! assert(shift (r, 3), [c, a, b]);
+%! assert(shift (r, -6), [c, a, b]);
+%! assert(shift (r, -3), [b, c, a]);
+%! assert(shift (m, 1), [c; a; b]);
+%! assert(shift (m, -2), [c; a; b]);
+
+%% Test input validation
+%!error shift ()
+%!error shift (1, 2, 3, 4)
+%!error shift ([], 1)
+%!error shift (ones(2), ones(2))
+%!error shift (ones(2), 1.5)
+%!error shift (1, 1, 1.5)
+%!error shift (1, 1, 0)
+%!error shift (1, 1, 3)
+