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
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