/usr/share/octave/packages/interval-2.1.0/@infsup/acos.m is in octave-interval 2.1.0-2.
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 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 | ## Copyright 2014-2016 Oliver Heimlich
##
## 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 -*-
## @documentencoding UTF-8
## @defmethod {@@infsup} acos (@var{X})
##
## Compute the inverse cosine in radians (arccosine).
##
## Accuracy: The result is a tight enclosure.
##
## @example
## @group
## acos (infsup (.5))
## @result{} ans ⊂ [1.0471, 1.0472]
## @end group
## @end example
## @seealso{@@infsup/cos}
## @end defmethod
## Author: Oliver Heimlich
## Keywords: interval
## Created: 2014-10-06
function x = acos (x)
if (nargin ~= 1)
print_usage ();
return
endif
persistent domain = infsup (-1, 1);
x = intersect (x, domain);
## acos is monotonically decreasing from (-1, pi) to (+1, 0)
if (__check_crlibm__ ())
l = crlibm_function ('acos', -inf, x.sup);
u = crlibm_function ('acos', +inf, x.inf);
else
l = mpfr_function_d ('acos', -inf, x.sup);
u = mpfr_function_d ('acos', +inf, x.inf);
endif
l(l == 0) = -0;
emptyresult = isempty (x);
l(emptyresult) = inf;
u(emptyresult) = -inf;
x.inf = l;
x.sup = u;
endfunction
%!# Empty interval
%!assert (acos (infsup ()) == infsup ());
%!# Singleton intervals
%!assert (acos (infsup (-1)) == infsup ("pi"));
%!assert (subset (acos (infsup (-.5)), union ((infsup ("pi") / 2), infsup ("pi"))));
%!assert (acos (infsup (0)) == infsup ("pi") / 2);
%!assert (subset (acos (infsup (.5)), union ((infsup ("pi") / 2), infsup (0))));
%!assert (acos (infsup (1)) == infsup (0));
%!# Bounded intervals
%!assert (acos (infsup (-1, 0)) == union ((infsup ("pi") / 2), infsup ("pi")));
%!assert (acos (infsup (0, 1)) == union ((infsup ("pi") / 2), infsup (0)));
%!assert (acos (infsup (-1, 1)) == infsup (0, "pi"));
%!assert (acos (infsup (-2, 2)) == infsup (0, "pi"));
%!# Unbounded intervals
%!assert (acos (infsup (0, inf)) == union ((infsup ("pi") / 2), infsup (0)));
%!assert (acos (infsup (-inf, 0)) == union ((infsup ("pi") / 2), infsup ("pi")));
%!assert (acos (infsup (-inf, inf)) == infsup (0, "pi"));
%!# from the documentation string
%!assert (acos (infsup (.5)) == "[0x1.0C152382D7365, 0x1.0C152382D7366]");
%!# correct use of signed zeros
%!test
%! x = acos (infsup (1));
%! assert (signbit (inf (x)));
%! assert (not (signbit (sup (x))));
|