/usr/share/plplot_octave/surfl.m is in octave-plplot 5.10.0+dfsg-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 57 58 59 60 61 62 | ## Copyright (C) 2001-2003 Joao Cardoso.
##
## 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 2, 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.
##
## This file is part of plplot_octave.
## usage: surfl ([x, y,] z [, s])
##
## Shaded Surface plot with lighting.
##
## If x, y, and z are matrices with the same dimensions,
## then corresponding elements represent vertices of the plot.
##
## If x and y are vectors, then a typical vertex is (x(j), y(i), z(i,j)). Thus,
## columns of z correspond to different x values and rows of z correspond
## to different y values.
##
## `s', if existent, set the light source in cartesian coordinates [Sx Sy Sz]
## or [Saz Sel] in spherical coordinates; in this case, the light source will
## be at a distance 10 from the origin.
## Ilumination can also be set by pllightsource(Sx, Sy, Sz)
function surfl (x, y, z, s)
global __pl
flag = 0;
if (nargin == 2)
s = y; flag = 1;
elseif (nargin == 1 || nargin == 3)
s = [10, 10, 10];
elseif (nargin == 4)
flag = 1;
endif
if (isvector(s))
if (length(s) == 2) ## [az, alt]
s = [10*cos(s(1)); 10*sin(s(1)); 10*sin(s(2))];
endif
else
error("surfl: s must be a vector\n");
endif
__pl.light = s;
if (nargin == 1 || (nargin == 2 && flag))
__pl_mesh ("surfl", x);
elseif (nargin == 3 || (nargin == 4 && flag))
__pl_mesh ("surfl", x, y, z);
else
help "surfl"
endif
endfunction
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