gaussian_2d.h

00001 /*
00002   -------------------------------------------------------------------
00003   
00004   Copyright (C) 2006, 2007, 2008, Andrew W. Steiner
00005   
00006   This file is part of O2scl.
00007   
00008   O2scl is free software; you can redistribute it and/or modify
00009   it under the terms of the GNU General Public License as published by
00010   the Free Software Foundation; either version 3 of the License, or
00011   (at your option) any later version.
00012   
00013   O2scl is distributed in the hope that it will be useful,
00014   but WITHOUT ANY WARRANTY; without even the implied warranty of
00015   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00016   GNU General Public License for more details.
00017   
00018   You should have received a copy of the GNU General Public License
00019   along with O2scl. If not, see <http://www.gnu.org/licenses/>.
00020 
00021   -------------------------------------------------------------------
00022 */
00023 #ifndef O2SCL_GAUSSIAN_2D_H
00024 #define O2SCL_GAUSSIAN_2D_H
00025 
00026 #include <o2scl/rnga.h>
00027 
00028 #ifndef DOXYGENP
00029 namespace o2scl {
00030 #endif
00031   
00032   /** 
00033       \brief Generate two random numbers from a normal distribution
00034       
00035       \todo Double check that sigma is implemented correctly
00036   */
00037   template<class rng_t> class gaussian_2d {
00038   public:
00039     
00040     rng_t r;
00041 
00042     /** \brief Generate two numbers from a 
00043         distribution with zero mean and standard deviation sigma
00044     */
00045     void random(double sigma, double &x, double &y) {
00046       
00047       double x1, x2, w, y1, y2;
00048       
00049       do {
00050         x1 = 2.0 * r.random() - 1.0;
00051         x2 = 2.0 * r.random() - 1.0;
00052         w = x1 * x1 + x2 * x2;
00053       } while ( w >= 1.0 );
00054       
00055       w = sqrt( (-2.0 * log( w ) ) / w );
00056       x = x1 * sigma * w;
00057       y = x2 * sigma * w;
00058       
00059       return;
00060     }
00061     
00062   };
00063 
00064 #ifndef DOXYGENP
00065 }
00066 #endif
00067 
00068 #endif

Documentation generated with Doxygen and provided under the GNU Free Documentation License. See License Information for details.

Project hosting provided by SourceForge.net Logo, O2scl Sourceforge Project Page