Mercurial > octave-nkf
view libinterp/corefcn/givens.cc @ 20653:9cef0a1207e4 @
cell2mat: add tests for cells of cells and char arrays
author | Carnë Draug <carandraug@octave.org> |
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date | Tue, 13 Oct 2015 11:40:05 +0100 |
parents | f90c8372b7ba |
children |
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/* Copyright (C) 1996-2015 John W. Eaton 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/>. */ // Originally written by A. S. Hodel <scotte@eng.auburn.edu> #ifdef HAVE_CONFIG_H #include <config.h> #endif #include "defun.h" #include "error.h" #include "oct-obj.h" DEFUN (givens, args, nargout, "-*- texinfo -*-\n\ @deftypefn {Built-in Function} {@var{G} =} givens (@var{x}, @var{y})\n\ @deftypefnx {Built-in Function} {[@var{c}, @var{s}] =} givens (@var{x}, @var{y})\n\ Compute the Givens rotation matrix @var{G}.\n\ \n\ @tex\n\ The Givens matrix is a $2\\times 2$ orthogonal matrix\n\ $$\n\ G = \\left[\\matrix{c & s\\cr -s'& c\\cr}\\right]\n\ $$\n\ such that\n\ $$\n\ G \\left[\\matrix{x\\cr y}\\right] = \\left[\\matrix{\\ast\\cr 0}\\right]\n\ $$\n\ with $x$ and $y$ scalars.\n\ @end tex\n\ @ifnottex\n\ The Givens matrix is a 2 by 2 orthogonal matrix\n\ \n\ @code{@var{g} = [@var{c} @var{s}; -@var{s}' @var{c}]}\n\ \n\ such that\n\ \n\ @code{@var{g} [@var{x}; @var{y}] = [*; 0]}\n\ \n\ with @var{x} and @var{y} scalars.\n\ @end ifnottex\n\ \n\ If two output arguments are requested, return the factors @var{c} and\n\ @var{s} rather than the Givens rotation matrix.\n\ \n\ For example:\n\ \n\ @example\n\ @group\n\ givens (1, 1)\n\ @result{} 0.70711 0.70711\n\ -0.70711 0.70711\n\ @end group\n\ @end example\n\ @seealso{planerot}\n\ @end deftypefn") { octave_value_list retval; int nargin = args.length (); if (nargin != 2 || nargout > 2) { print_usage (); return retval; } else { if (args(0).is_single_type () || args(1).is_single_type ()) { if (args(0).is_complex_type () || args(1).is_complex_type ()) { 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(0) = result; break; case 2: retval(1) = result (0, 1); retval(0) = result (0, 0); 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(0) = result; break; case 2: retval(1) = result (0, 1); retval(0) = result (0, 0); break; } } } else { if (args(0).is_complex_type () || args(1).is_complex_type ()) { Complex cx = args(0).complex_value (); Complex cy = args(1).complex_value (); ComplexMatrix result = Givens (cx, cy); switch (nargout) { case 0: case 1: retval(0) = result; break; case 2: retval(1) = result (0, 1); retval(0) = result (0, 0); 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(0) = result; break; case 2: retval(1) = result (0, 1); retval(0) = result (0, 0); 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) */