Mercurial > octave-nkf
view libinterp/corefcn/givens.cc @ 20651:e54ecb33727e
lo-array-gripes.cc: Remove FIXME's related to buffer size.
* lo-array-gripes.cc: Remove FIXME's related to buffer size. Shorten sprintf
buffers from 100 to 64 characters (still well more than 19 required).
Use 'const' decorator on constant value for clarity. Remove extra space
between variable and array bracket.
author | Rik <rik@octave.org> |
---|---|
date | Mon, 12 Oct 2015 21:13:47 -0700 |
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) */