/usr/share/octave/packages/interval-2.1.0/@infsup/diag.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 | ## Copyright 2015-2016 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
## @deftypemethod {@@infsup} {M =} diag (@var{V})
## @deftypemethodx {@@infsup} {V =} diag (@var{M})
## @deftypemethodx {@@infsup} {M =} diag (@var{V}, @var{K})
## @deftypemethodx {@@infsup} {M =} diag (@var{V}, @var{M}, @var{N})
## @deftypemethodx {@@infsup} {V =} diag (@var{M}, @var{K})
##
## Create a diagonal matrix @var{M} with vector @var{V} on diagonal @var{K} or
## extract a vector @var{V} from the @var{K}-th diagonal of matrix @var{M}.
##
## With three arguments, create a matrix of size @var{M}×@var{N}.
##
## @example
## @group
## diag (infsup (1 : 3))
## @result{} ans = 3×3 interval matrix
##
## [1] [0] [0]
## [0] [2] [0]
## [0] [0] [3]
## @end group
## @end example
## @seealso{@@infsup/tril, @@infsup/triu}
## @end deftypemethod
## Author: Oliver Heimlich
## Keywords: interval
## Created: 2015-10-23
function x = diag (x, varargin)
if (nargin >= 2 && isa (m, 'infsup'))
error ('diag: invalid second argument; it must not be an interval');
endif
if (nargin >= 3 && isa (n, 'infsup'))
error ('diag: invalid third argument; it must not be an interval');
endif
if (nargin > 3)
print_usage ();
return
endif
l = diag (x.inf, varargin{:});
u = diag (x.sup, varargin{:});
l(l == 0) = -0;
x.inf = l;
x.sup = u;
endfunction
%!assert (diag (infsup (-inf, inf)) == "[Entire]");
%!assert (diag (infsup ()) == "[Empty]");
%!assert (numel (diag (infsup ([]))), 0);
%!assert (isequal (diag (infsup (magic (3))), infsup ([8; 5; 2])));
%!assert (isequal (diag (infsup ([8 5 3])), infsup ([8 0 0; 0 5 0; 0 0 3])));
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