Mercurial > octave
view scripts/general/idivide.m @ 31198:863730dd0f83 stable
nextpow2: Fix for input between 0.5 and 1 (bug #62947).
* scripts/general/nextpow2.m: Switch to a naïve implementation using log2 with
a single output argument and ceil.
author | Markus Mützel <markus.muetzel@gmx.de> |
---|---|
date | Wed, 24 Aug 2022 17:15:34 +0200 |
parents | 290e7e3f859f |
children | 5d3faba0342e |
line wrap: on
line source
######################################################################## ## ## Copyright (C) 2008-2022 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 {} {} idivide (@var{x}, @var{y}, @var{op}) ## Integer division with different rounding rules. ## ## The standard behavior of integer division such as @code{@var{a} ./ @var{b}} ## is to round the result to the nearest integer. This is not always the ## desired behavior and @code{idivide} permits integer element-by-element ## division to be performed with different treatment for the fractional ## part of the division as determined by the @var{op} flag. @var{op} is ## a string with one of the values: ## ## @table @asis ## @item @qcode{"fix"} ## Calculate @code{@var{a} ./ @var{b}} with the fractional part rounded ## towards zero. ## ## @item @qcode{"round"} ## Calculate @code{@var{a} ./ @var{b}} with the fractional part rounded ## towards the nearest integer. ## ## @item @qcode{"floor"} ## Calculate @code{@var{a} ./ @var{b}} with the fractional part rounded ## towards negative infinity. ## ## @item @qcode{"ceil"} ## Calculate @code{@var{a} ./ @var{b}} with the fractional part rounded ## towards positive infinity. ## @end table ## ## @noindent ## If @var{op} is not given it defaults to @qcode{"fix"}. ## An example demonstrating these rounding rules is ## ## @example ## @group ## idivide (int8 ([-3, 3]), int8 (4), "fix") ## @result{} 0 0 ## idivide (int8 ([-3, 3]), int8 (4), "round") ## @result{} -1 1 ## idivide (int8 ([-3, 3]), int8 (4), "floor") ## @result{} -1 0 ## idivide (int8 ([-3, 3]), int8 (4), "ceil") ## @result{} 0 1 ## @end group ## @end example ## ## @seealso{ldivide, rdivide} ## @end deftypefn function z = idivide (x, y, op) if (nargin < 2) print_usage (); endif if (nargin == 2) op = "fix"; else op = tolower (op); endif if (! isinteger (x) && ! isinteger (y)) error ("idivide: at least one input (X or Y) must be an integer type"); elseif (isinteger (x) && isinteger (y) && ! strcmp (class (x), class (y))) error ("idivide: integer type of X (%s) must match integer type of Y (%s)", class (x), class (y)); endif z = x ./ y; if (strcmp (op, "fix")) ## The following is an optimized version of `z -= (z .* y > x) .* sign (y)`. if (isscalar (y)) if (y > 0) z -= (z * y > x); else z += (z * y > x); endif else y_sel = (y > 0); if (isscalar (x)) z(y_sel) -= (z(y_sel) .* y(y_sel) > x); y_sel = ! y_sel; z(y_sel) += (z(y_sel) .* y(y_sel) > x); else z(y_sel) -= (z(y_sel) .* y(y_sel) > x(y_sel)); y_sel = ! y_sel; z(y_sel) += (z(y_sel) .* y(y_sel) > x(y_sel)); endif endif elseif (strcmp (op, "round")) return; elseif (strcmp (op, "floor")) ## The following is an optimized version of `z -= (z .* abs (y) > sign (y) .* x)`. if (isscalar (y)) if (y > 0) z -= (z * y > x); else z -= (z * y < x); endif else y_sel = (y > 0); if (isscalar (x)) z(y_sel) -= (z(y_sel) .* y(y_sel) > x); y_sel = ! y_sel; z(y_sel) -= (z(y_sel) .* y(y_sel) < x); else z(y_sel) -= (z(y_sel) .* y(y_sel) > x(y_sel)); y_sel = ! y_sel; z(y_sel) -= (z(y_sel) .* y(y_sel) < x(y_sel)); endif endif elseif (strcmp (op, "ceil")) ## The following is an optimized version of `z += (z .* abs (y) < sign (y) .* x)`. if (isscalar (y)) if (y > 0) z += (z * y < x); else z += (z * y > x); endif else y_sel = (y > 0); if (isscalar (x)) z(y_sel) += (z(y_sel) .* y(y_sel) < x); y_sel = ! y_sel; z(y_sel) += (z(y_sel) .* y(y_sel) > x); else z(y_sel) += (z(y_sel) .* y(y_sel) < x(y_sel)); y_sel = ! y_sel; z(y_sel) += (z(y_sel) .* y(y_sel) > x(y_sel)); endif endif else error ('idivide: unrecognized rounding type "%s"', op); endif endfunction %!shared a, af, b, bf %! a = int8 (3); %! af = 3; %! b = int8 ([-4, 4]); %! bf = [-4, 4]; %!assert (idivide (a, b), int8 ([0, 0])) %!assert (idivide (a, b, "floor"), int8 ([-1, 0])) %!assert (idivide (a, b, "ceil"), int8 ([0, 1])) %!assert (idivide (a, b, "round"), int8 ([-1, 1])) %!assert (idivide (af, b), int8 ([0, 0])) %!assert (idivide (af, b, "floor"), int8 ([-1, 0])) %!assert (idivide (af, b, "ceil"), int8 ([0, 1])) %!assert (idivide (af, b, "round"), int8 ([-1, 1])) %!assert (idivide (a, bf), int8 ([0, 0])) %!assert (idivide (a, bf, "floor"), int8 ([-1, 0])) %!assert (idivide (a, bf, "ceil"), int8 ([0, 1])) %!assert (idivide (a, bf, "round"), int8 ([-1, 1])) %!shared c, d %! c = int64 (4e16); %! d = int64 ([-2e8, 2e8]); %!assert <*61319> (idivide (c, d + int64 (1)), d + int64 ([-1, -1])) %!assert <*61319> (idivide (c, d + int64 (1), "floor"), d + int64 ([-2, -1])) %!assert <*61319> (idivide (c, d + int64 (1), "ceil"), d + int64 ([-1, 0])) %!assert <*61319> (idivide (c, d + int64 (1), "round"), d + int64 ([-1, -1])) %!assert <*61319> (idivide (c + int64 (1), d), d) %!assert <*61319> (idivide (c + int64 (1), d, "floor"), d + int64 ([-1, 0])) %!assert <*61319> (idivide (c + int64 (1), d, "ceil"), d + int64 ([0, 1])) %!assert <*61319> (idivide (c + int64 (1), d, "round"), d) ## Test input validation %!error idivide (uint8 (1)) %!error idivide (uint8 (1), 2, 3) %!error <at least one input> idivide (1, 2) %!error <at least one input> idivide ({1}, 2) %!error <X \(int8\) must match.* Y \(uint8\)> idivide (int8 (1), uint8 (2)) %!error <unrecognized rounding type "foo"> idivide (int8 (1), 2, "foo")