Mercurial > octave
view scripts/general/nextpow2.m @ 23219:3ac9f9ecfae5 stable
maint: Update copyright dates.
author | John W. Eaton <jwe@octave.org> |
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date | Wed, 22 Feb 2017 12:39:29 -0500 |
parents | e9a0469dedd9 |
children | 092078913d54 |
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## Copyright (C) 1995-2017 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 {} {} nextpow2 (@var{x}) ## Compute the exponent for the smallest power of two larger than the input. ## ## For each element in the input array @var{x}, return the first integer ## @var{n} such that ## @tex ## $2^n \ge |x|$. ## @end tex ## @ifnottex ## 2^n @geq{} abs (x). ## @end ifnottex ## ## @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 (! isnumeric (x)) error ("nextpow2: X must be numeric"); endif [f, n] = log2 (abs (x)); n(f == 0.5)--; endfunction %!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), [0 1 2 2 3 3 3 3 4 4 4 4 4 4 4 4 5]) %!error nexpow2 () %!error nexpow2 (1, 2)