update packages

[CreaPhase.git] / octave_packages / m / general / nextpow2.m

diff --git a/octave_packages/m/general/nextpow2.m b/octave_packages/m/general/nextpow2.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} {} nextpow2 (@var{x})
+## If @var{x} is a scalar, return the first integer @var{n} such that
+## @tex
+## $2^n \ge |x|$.
+## @end tex
+## @ifnottex
+## 2^n @geq{} abs (x).
+## @end ifnottex
+##
+## If @var{x} is a vector, return @code{nextpow2 (length (@var{x}))}.
+## @seealso{pow2, log2}
+## @end deftypefn
+
+## Author: KH <Kurt.Hornik@wu-wien.ac.at>
+## Created: 7 October 1994
+## Adapted-By: jwe
+
+function n = nextpow2 (x)
+
+  if (nargin != 1)
+    print_usage ();
+  endif
+
+  if (! (isscalar (x) || isvector (x)))
+    error ("nextpow2: X must be a scalar or a vector");
+  endif
+
+  t = length (x);
+  if (t > 1)
+    x = t;
+  endif
+
+  [f, n] = log2 (abs (x));
+  if (f == 0.5)
+    n = n - 1;
+  endif
+
+endfunction
+
+%!error nexpow2 ();
+%!error nexpow2 (1, 2);
+
+%!assert (nextpow2 (16), 4);
+%!assert (nextpow2 (17), 5);
+%!assert (nextpow2 (31), 5);
+%!assert (nextpow2 (-16), 4);
+%!assert (nextpow2 (-17), 5);
+%!assert (nextpow2 (-31), 5);
+%!assert (nextpow2 (1:17), 5);