/usr/share/octave/packages/specfun-1.1.0/Si.m is in octave-specfun 1.1.0-4.
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 | ## Copyright (C) 2006 Sylvain Pelissier <sylvain.pelissier@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{y} =} Si (@var{x})
## Compute the sine integral defined by:
## @verbatim
## x
## /
## Si(x) = | sin(t)/t dt
## /
## 0
## @end verbatim
## @end deftypefn
function y = Si(x)
if (nargin != 1)
print_usage;
endif
y = zeros(size(x));
if prod(size(x)) < 101
for k = 1:prod(size(x))
y(k) = sum(besselj([0:100]+0.5,(x(k)/2)).^2);
endfor
y = y.*pi;
else
for k=0:100
y += besselj(k+0.5,x/2).^2;
endfor
y = y.*pi;
endif
endfunction
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