/********************************************************************
**                Image Component Library (ICL)                    **
**                                                                 **
** Copyright (C) 2006-2013 CITEC, University of Bielefeld          **
**                         Neuroinformatics Group                  **
** Website: www.iclcv.org and                                      **
**          http://opensource.cit-ec.de/projects/icl               **
**                                                                 **
** File   : ICLUtils/src/ICLUtils/Random.cpp                       **
** Module : ICLUtils                                               **
** Authors: Christof Elbrechter                                    **
**                                                                 **
**                                                                 **
** GNU LESSER GENERAL PUBLIC LICENSE                               **
** This file may be used under the terms of the GNU Lesser General **
** Public License version 3.0 as published by the                  **
**                                                                 **
** Free Software Foundation and appearing in the file LICENSE.LGPL **
** included in the packaging of this file.  Please review the      **
** following information to ensure the license requirements will   **
** be met: http://www.gnu.org/licenses/lgpl-3.0.txt                **
**                                                                 **
** The development of this software was supported by the           **
** Excellence Cluster EXC 277 Cognitive Interaction Technology.    **
** The Excellence Cluster EXC 277 is a grant of the Deutsche       **
** Forschungsgemeinschaft (DFG) in the context of the German       **
** Excellence Initiative.                                          **
**                                                                 **
********************************************************************/

#include <ICLUtils/Random.h>

namespace icl{
  namespace utils{
    
    double gaussRandom(double mu, double sigma){
      static bool haveNextGaussian = false;
      static double nextGaussian = 0;
      if(haveNextGaussian){
        haveNextGaussian = false;
        return nextGaussian*sigma + mu;
      } else{
        double v1(0), v2(0), s(0);
        do{
          v1 = 2 * random(1.0)-1;
          v2 = 2 * random(1.0)-1;
          s = v1*v1 + v2*v2;
        }while(s>=1 || s == 0);
        double fac = sqrt(-2.0*log(s)/s);
        nextGaussian = v2 * fac;
        haveNextGaussian = true;
        return v1 * fac * sigma + mu;
      }
    }   
  
    
  } // namespace utils
}