Mercurial > octave
view libinterp/corefcn/rcond.cc @ 23084:ef4d915df748
maint: Merge stable to default.
author | John W. Eaton <jwe@octave.org> |
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date | Mon, 23 Jan 2017 14:27:48 -0500 |
parents | 3a2b891d0b33 e9a0469dedd9 |
children | 092078913d54 |
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/* Copyright (C) 2008-2016 David Bateman 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 <http://www.gnu.org/licenses/>. */ #if defined (HAVE_CONFIG_H) # include "config.h" #endif #include "defun.h" #include "error.h" #include "errwarn.h" #include "ovl.h" #include "utils.h" DEFUN (rcond, args, , doc: /* -*- texinfo -*- @deftypefn {} {@var{c} =} rcond (@var{A}) Compute the 1-norm estimate of the reciprocal condition number as returned by @sc{lapack}. If the matrix is well-conditioned then @var{c} will be near 1 and if the matrix is poorly conditioned it will be close to 0. The matrix @var{A} must not be sparse. If the matrix is sparse then @code{condest (@var{A})} or @code{rcond (full (@var{A}))} should be used instead. @seealso{cond, condest} @end deftypefn */) { if (args.length () != 1) print_usage (); octave_value retval; if (args(0).is_sparse_type ()) error ("rcond: for sparse matrices use 'rcond (full (a))' or 'condest (a)' instead"); if (args(0).is_single_type ()) { if (args(0).is_complex_type ()) { FloatComplexMatrix m = args(0).float_complex_matrix_value (); MatrixType mattyp; retval = m.rcond (mattyp); args(0).matrix_type (mattyp); } else { FloatMatrix m = args(0).float_matrix_value (); MatrixType mattyp; retval = m.rcond (mattyp); args(0).matrix_type (mattyp); } } else if (args(0).is_complex_type ()) { ComplexMatrix m = args(0).complex_matrix_value (); MatrixType mattyp; retval = m.rcond (mattyp); args(0).matrix_type (mattyp); } else { Matrix m = args(0).matrix_value (); MatrixType mattyp; retval = m.rcond (mattyp); args(0).matrix_type (mattyp); } return retval; } /* %!assert (rcond (eye (2)), 1) %!assert (rcond (ones (2)), 0) %!assert (rcond ([1 1; 2 1]), 1/9) %!assert (rcond (magic (4)), 0, eps) %!shared x, sx %! x = [-5.25, -2.25; -2.25, 1] * eps () + ones (2) / 2; %! sx = [-5.25, -2.25; -2.25, 1] * eps ("single") + ones (2) / 2; %!assert (rcond (x) < eps ()) %!assert (rcond (sx) < eps ('single')) %!assert (rcond (x*i) < eps ()) %!assert (rcond (sx*i) < eps ('single')) */