Mercurial > octave
view scripts/general/nextpow2.m @ 33533:e89b2f30867d bytecode-interpreter tip
maint: Merge default to bytecode-interpreter
author | Arun Giridhar <arungiridhar@gmail.com> |
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date | Sun, 05 May 2024 18:12:44 -0400 |
parents | 297fd823a953 |
children |
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######################################################################## ## ## Copyright (C) 1995-2024 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this ## distribution or <https://octave.org/copyright/>. ## ## 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 ## <https://www.gnu.org/licenses/>. ## ######################################################################## ## -*- texinfo -*- ## @deftypefn {} {@var{n} =} nextpow2 (@var{x}) ## Compute the exponent of the next power of two not smaller than the input. ## ## For each element in the input array @var{x}, return the smallest integer ## @var{n} such that ## @tex ## $2^n \ge |x|$. ## @end tex ## @ifnottex ## @code{2^@var{n} @geq{} abs (@var{x})}. ## @end ifnottex ## For input elements equal to zero, return zero. ## ## @seealso{pow2, log2} ## @end deftypefn function n = nextpow2 (x) if (nargin < 1) print_usage (); endif if (! isnumeric (x)) error ("nextpow2: X must be numeric"); elseif (! isreal (x)) error ("nextpow2: X must be real"); endif [f, n] = log2 (abs (x)); n(f == 0.5)--; if (isfloat (x)) idx_nan = isnan (x); n(idx_nan) = x(idx_nan); n(isinf (x)) = Inf; else n = cast (n, class (x)); if (intmax (x) > flintmax ()) n((2 .^ n) < abs (x))++; endif endif 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]) %!assert <*62947> (nextpow2 (0.5), -1) %!assert <*62947> (nextpow2 (0.6), 0) ## Special cases %!assert (nextpow2 (0), 0) %!assert (nextpow2 (1), 0) %!assert (nextpow2 (Inf), Inf) %!assert (nextpow2 (-Inf), Inf) %!assert (nextpow2 (NaN), NaN) %!assert (nextpow2 (NA), NA) %!assert (nextpow2 ([1, Inf, 3, -Inf, 9, NaN, NA]), ... %! [0, Inf, 2, Inf, 4, NaN, NA]) %!test %! p = (-1074:1023).'; %! x = 2 .^ p; %! x = [x, x + eps(x)]; %! x = [x, -x]; %! n = nextpow2 (x); %! assert (n(:, 1), p); %! assert (n(:, 3), p); %! assert (n(:, 2), p + 1); %! assert (n(:, 4), p + 1); %!assert (nextpow2 (realmax ()), 1024) %!assert (nextpow2 (-realmax ()), 1024) %!test %! p = single (-149:127).'; %! x = 2 .^ p; %! x = [x, x + eps(x)]; %! x = [x, -x]; %! n = nextpow2 (x); %! assert (n(:, 1), p); %! assert (n(:, 3), p); %! assert (n(:, 2), p + 1); %! assert (n(:, 4), p + 1); %!assert (nextpow2 (realmax ('single')), single (128)) %!assert (nextpow2 (-realmax ('single')), single (128)) %!test %! p = int32 (0:30).'; %! x = 2 .^ p; %! x = [x, x + 1]; %! x = [x, -x]; %! n = nextpow2 (x); %! assert (n(:, 1), p); %! assert (n(:, 3), p); %! assert (n(:, 2), p + 1); %! assert (n(:, 4), p + 1); %!assert (nextpow2 (int32 (0)), int32 (0)) %!assert (nextpow2 (intmin ('int32')), int32 (31)) %!assert (nextpow2 (intmax ('int32')), int32 (31)) %!assert (nextpow2 (uint32 (0)), uint32 (0)) %!assert (nextpow2 (intmax ('uint32')), uint32 (32)) %!test %! p = int64 (0:62).'; %! x = 2 .^ p; %! x = [x, x + 1]; %! x = [x, -x]; %! n = nextpow2 (x); %! assert (n(:, 1), p); %! assert (n(:, 3), p); %! assert (n(:, 2), p + 1); %! assert (n(:, 4), p + 1); %!assert (nextpow2 (int64 (0)), int64 (0)) %!assert (nextpow2 (intmin ('int64')), int64 (63)) %!assert (nextpow2 (intmax ('int64')), int64 (63)) %!assert (nextpow2 (uint64 (0)), uint64 (0)) %!assert (nextpow2 (intmax ('uint64')), uint64 (64)) ## Test input validation %!error <Invalid call> nextpow2 () %!error <X must be numeric> nextpow2 ("t") %!error <X must be real> nextpow2 (1 + 2i)