/usr/share/octave/packages/interval-2.1.0/@infsupdec/pow.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
## @defmethod {@@infsupdec} pow (@var{X}, @var{Y})
##
## Compute the simple power function on intervals defined by
## @code{exp (@var{Y} * log (@var{X}))}.
##
## The function is only defined where @var{X} is positive or where @var{X} is
## zero and @var{Y} is positive.
##
## Accuracy: The result is a tight enclosure.
##
## @example
## @group
## pow (infsupdec (5, 6), infsupdec (2, 3))
## @result{} ans = [25, 216]_com
## @end group
## @end example
## @seealso{@@infsupdec/pown, @@infsupdec/pow2, @@infsupdec/pow10, @@infsupdec/exp, @@infsupdec/mpower}
## @end defmethod
## Author: Oliver Heimlich
## Keywords: interval
## Created: 2014-10-13
function result = pow (x, y)
if (nargin ~= 2)
print_usage ();
return
endif
if (not (isa (x, "infsupdec")))
x = infsupdec (x);
endif
if (not (isa (y, "infsupdec")))
y = infsupdec (y);
endif
result = newdec (pow (x.infsup, y.infsup));
## pow is continuous everywhere (where it is defined),
## but defined for x > 0 or (x = 0 and y > 0) only
persistent nonnegative = infsup (0, inf);
domain = interior (x.infsup, nonnegative) | ...
(subset (x.infsup, nonnegative) & interior (y.infsup, nonnegative));
result.dec(not (domain)) = _trv ();
result.dec = min (result.dec, min (x.dec, y.dec));
endfunction
%!# from the documentation string
%!assert (isequal (pow (infsupdec (5, 6), infsupdec (2, 3)), infsupdec (25, 216)));
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