/usr/share/octave/packages/image-2.2.2/colorgradient.m is in octave-image 2.2.2-1.
This file is owned by root:root, with mode 0o644.
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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 | ## Author: Paul Kienzle <pkienzle@users.sf.net>
## This program is granted to the public domain.
## -*- texinfo -*-
## @deftypefn {Function File} {@var{M} =} colorgradient (@var{C}, @var{w}, @var{n})
## Define a colour map which smoothly traverses the given colors.
## @var{C} contains the colours, one row per r,g,b value.
## @var{w}(i) is the relative length of the transition from colour i to colour i+1
## in the entire gradient. The default is ones(rows(C)-1,1).
## n is the length of the colour map. The default is rows(colormap).
##
## E.g.,
## @example
## colorgradient([0,0,1; 1,1,0; 1,0,0]) # blue -> yellow -> red
## x = linspace(0,1,200);
## imagesc(x(:,ones(30,1)))';
## @end example
## @end deftypefn
function ret = colorgradient (C, w, n)
if nargin < 1 || nargin > 3
print_usage;
endif
if nargin == 1
n = rows(colormap);
w = ones(length(C)-1,1);
elseif nargin == 2
if (length(w) == 1)
n = w;
w = ones(rows(C)-1,1);
else
n = rows(colormap);
endif
endif
if (length(w)+1 != rows(C))
error("must have one weight for each color interval");
endif
w = 1+round((n-1)*cumsum([0;w(:)])/sum(w));
map = zeros(n,3);
for i=1:length(w)-1
if (w(i) != w(i+1))
map(w(i):w(i+1),1) = linspace(C(i,1),C(i+1,1),w(i+1)-w(i)+1)';
map(w(i):w(i+1),2) = linspace(C(i,2),C(i+1,2),w(i+1)-w(i)+1)';
map(w(i):w(i+1),3) = linspace(C(i,3),C(i+1,3),w(i+1)-w(i)+1)';
endif
endfor
if nargout == 0
colormap(map);
else
ret = map;
endif
endfunction
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