Mercurial > octave-libtiff
view libinterp/corefcn/givens.cc @ 30564:796f54d4ddbf stable
update Octave Project Developers copyright for the new year
In files that have the "Octave Project Developers" copyright notice,
update for 2021.
In all .txi and .texi files except gpl.txi and gpl.texi in the
doc/liboctave and doc/interpreter directories, change the copyright
to "Octave Project Developers", the same as used for other source
files. Update copyright notices for 2022 (not done since 2019). For
gpl.txi and gpl.texi, change the copyright notice to be "Free Software
Foundation, Inc." and leave the date at 2007 only because this file
only contains the text of the GPL, not anything created by the Octave
Project Developers.
Add Paul Thomas to contributors.in.
author | John W. Eaton <jwe@octave.org> |
---|---|
date | Tue, 28 Dec 2021 18:22:40 -0500 |
parents | 32c3a5805893 |
children |
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//////////////////////////////////////////////////////////////////////// // // Copyright (C) 1996-2022 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/>. // //////////////////////////////////////////////////////////////////////// // Originally written by A. S. Hodel <scotte@eng.auburn.edu> #if defined (HAVE_CONFIG_H) # include "config.h" #endif #include "defun.h" #include "error.h" #include "ovl.h" OCTAVE_NAMESPACE_BEGIN DEFUN (givens, args, nargout, doc: /* -*- texinfo -*- @deftypefn {} {@var{G} =} givens (@var{x}, @var{y}) @deftypefnx {} {[@var{c}, @var{s}] =} givens (@var{x}, @var{y}) Compute the Givens rotation matrix @var{G}. @tex The Givens matrix is a $2\times 2$ orthogonal matrix $$ G = \left[\matrix{c & s\cr -s'& c\cr}\right] $$ such that $$ G \left[\matrix{x\cr y}\right] = \left[\matrix{\ast\cr 0}\right] $$ with $x$ and $y$ scalars. @end tex @ifnottex The Givens matrix is a 2-by-2 orthogonal matrix @example @group @var{G} = [ @var{c} , @var{s} -@var{s}', @var{c}] @end group @end example @noindent such that @example @var{G} * [@var{x}; @var{y}] = [*; 0] @end example @noindent with @var{x} and @var{y} scalars. @end ifnottex If two output arguments are requested, return the factors @var{c} and @var{s} rather than the Givens rotation matrix. For example: @example @group givens (1, 1) @result{} 0.70711 0.70711 -0.70711 0.70711 @end group @end example Note: The Givens matrix represents a counterclockwise rotation of a 2-D plane and can be used to introduce zeros into a matrix prior to complete factorization. @seealso{planerot, qr} @end deftypefn */) { if (args.length () != 2) print_usage (); octave_value_list retval; if (args(0).is_single_type () || args(1).is_single_type ()) { if (args(0).iscomplex () || args(1).iscomplex ()) { FloatComplex cx = args(0).float_complex_value (); FloatComplex cy = args(1).float_complex_value (); FloatComplexMatrix result = Givens (cx, cy); switch (nargout) { case 0: case 1: retval = ovl (result); break; case 2: retval = ovl (result(0, 0), result(0, 1)); break; } } else { float x = args(0).float_value (); float y = args(1).float_value (); FloatMatrix result = Givens (x, y); switch (nargout) { case 0: case 1: retval = ovl (result); break; case 2: retval = ovl (result(0, 0), result(0, 1)); break; } } } else { if (args(0).iscomplex () || args(1).iscomplex ()) { Complex cx = args(0).complex_value (); Complex cy = args(1).complex_value (); ComplexMatrix result = Givens (cx, cy); switch (nargout) { case 0: case 1: retval = ovl (result); break; case 2: retval = ovl (result(0, 0), result(0, 1)); break; } } else { double x = args(0).double_value (); double y = args(1).double_value (); Matrix result = Givens (x, y); switch (nargout) { case 0: case 1: retval = ovl (result); break; case 2: retval = ovl (result(0, 0), result(0, 1)); break; } } } return retval; } /* %!assert (givens (1,1), [1, 1; -1, 1] / sqrt (2), 2*eps) %!assert (givens (1,0), eye (2)) %!assert (givens (0,1), [0, 1; -1 0]) %!error givens () %!error givens (1) %!error [a,b,c] = givens (1, 1) */ OCTAVE_NAMESPACE_END