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########################################################################
##
## Copyright (C) 1999-2024 The Octave Project Developers
##
## See the file COPYRIGHT.md in the top-level directory of this
## distribution or <https://octave.org/copyright/>.
##
## This file is part of Octave.
##
## Octave 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.
##
## Octave 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 Octave; see the file COPYING. If not, see
## <https://www.gnu.org/licenses/>.
##
########################################################################
## -*- texinfo -*-
## @deftypefn {} {@var{R} =} rosser ()
## Return the @nospell{Rosser} matrix.
##
## This is a difficult test case used to evaluate eigenvalue algorithms.
## @seealso{wilkinson, eig}
## @end deftypefn
function R = rosser ()
R = [611, 196, -192, 407, -8, -52, -49, 29;
196, 899, 113, -192, -71, -43, -8, -44;
-192, 113, 899, 196, 61, 49, 8, 52;
407, -192, 196, 611, 8, 44, 59, -23;
-8, -71, 61, 8, 411, -599, 208, 208;
-52, -43, 49, 44, -599, 411, 208, 208;
-49, -8, 8, 59, 208, 208, 99, -911;
29, -44, 52, -23, 208, 208, -911, 99];
endfunction
%!assert (size (rosser ()), [8,8])
%!assert (rosser ()([1, end]), [611, 99])
%!error rosser (1)
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