/usr/share/octave/packages/interval-2.1.0/@infsupdec/cosrev.m is in octave-interval 2.1.0-2.
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##
## 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
## @deftypemethod {@@infsupdec} {@var{X} =} cosrev (@var{C}, @var{X})
## @deftypemethodx {@@infsupdec} {@var{X} =} cosrev (@var{C})
##
## Compute the reverse cosine function.
##
## That is, an enclosure of all @code{x ∈ @var{X}} where
## @code{cos (x) ∈ @var{C}}.
##
## Accuracy: The result is a valid enclosure.
##
## @comment DO NOT SYNCHRONIZE DOCUMENTATION STRING
## No one way of decorating this operations gives useful information in all
## contexts. Therefore, the result will carry a @code{trv} decoration at best.
##
## @example
## @group
## cosrev (infsupdec (0), infsupdec (6, 9))
## @result{} ans ⊂ [7.8539, 7.854]_trv
## @end group
## @end example
## @seealso{@@infsupdec/cos}
## @end deftypemethod
## Author: Oliver Heimlich
## Keywords: interval
## Created: 2014-10-19
function result = cosrev (c, x)
if (nargin > 2)
print_usage ();
return
endif
if (nargin < 2)
x = infsupdec (-inf, inf);
endif
if (not (isa (c, "infsupdec")))
c = infsupdec (c);
endif
if (not (isa (x, "infsupdec")))
x = infsupdec (x);
endif
result = infsupdec (cosrev (c.infsup, x.infsup), "trv");
result.dec(isnai (c) | isnai (x)) = _ill ();
endfunction
%!# from the documentation string
%!assert (isequal (cosrev (0, infsupdec (6, 9)), infsupdec ("[0x1.F6A7A2955385Ep2, 0x1.F6A7A2955386p2]_trv")));
|