/usr/share/octave/packages/image-2.2.2/immultiply.m is in octave-image 2.2.2-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 | ## Copyright (C) 2011 Carnë Draug <carandraug+dev@gmail.com>
##
## This program 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.
##
## This program 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
## this program; if not, see <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {Function File} {@var{out} =} immultiply (@var{a}, @var{b})
## @deftypefnx {Function File} {@var{out} =} immultiply (@var{a}, @var{b}, @var{class})
## Multiply image by another image or constant.
##
## If @var{a} and @var{b} are two images of same size and class, the images are
## multiplied. Alternatively, if @var{b} is a floating-point scalar, @var{a} is
## multiplie by it.
##
## The class of @var{out} will be the same as @var{a} unless @var{a} is logical
## in which case @var{out} will be double. Alternatively, it can be
## specified with @var{class}.
##
## @emph{Note}: the values are truncated to the mininum value of the output
## class.
## @seealso{imabsdiff, imadd, imcomplement, imdivide, imlincomb, imsubtract}
## @end deftypefn
function img = immultiply (img, val, out_class = class (img))
if (nargin < 2 || nargin > 3)
print_usage;
endif
[img, val] = imarithmetics ("immultiply", img, val, out_class, nargin);
## have to check how matlab behaves in this situtation. Their documentation
## does not say anything but add and subtract silently ignore it and return
## double anyway. This may be done in the call to imarithmetics
if (nargin > 2 && strcmpi (out_class, "logical"))
warning ("Ignoring request to return logical as output of multiplication.");
endif
img = img .* val;
endfunction
%!assert (immultiply (uint8 ([255 50]), uint16 ([300 50])), uint8 ([255 255])); # default to first class and truncate
%!assert (immultiply (uint8 ([250 50]), uint16 ([ 3 4]), "uint32"), uint32 ([750 200])); # defining output class works (not in matlab?)
%!assert (immultiply (uint8 ([255 50]), 4), uint8 ([255 200])); # works multiplying by a scalar
%!assert (immultiply (logical ([ 1 0]), uint16 ([300 50])), uint16 ([300 0])); # output class defaults to whatever input is not logical
%!assert (immultiply (logical ([ 1 0]), logical ([ 1 1])), double ([ 1 0])); # tested on matlab for compatibility
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