/usr/share/octave/packages/interval-2.1.0/@infsupdec/realsqrt.m is in octave-interval 2.1.0-2.
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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 | ## 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 {@@infsupdec} realsqrt (@var{X})
##
## Compute the square root (for all non-negative numbers).
##
## Accuracy: The result is a tight enclosure.
##
## @example
## @group
## realsqrt (infsupdec (-6, 4))
## @result{} ans = [0, 2]_trv
## @end group
## @end example
## @seealso{@@infsupdec/sqr, @@infsupdec/rsqrt, @@infsupdec/pow, @@infsupdec/cbrt, @@infsupdec/nthroot}
## @end defmethod
## Author: Oliver Heimlich
## Keywords: interval
## Created: 2014-10-13
function result = realsqrt (x)
if (nargin ~= 1)
print_usage ();
return
endif
result = newdec (realsqrt (x.infsup));
## realsqrt is continuous everywhere, but defined for x >= 0 only
persistent domain = infsup (0, inf);
defined = subset (x.infsup, domain);
result.dec(not (defined)) = _trv ();
result.dec = min (result.dec, x.dec);
endfunction
%!# from the documentation string
%!assert (isequal (realsqrt (infsupdec (-6, 4)), infsupdec (0, 2, "trv")));
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