Random.h

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/*      
 * File: Random.h
 * Project: DUtils library
 * Author: Dorian Galvez-Lopez
 * Date: April 2010
 * Description: manages pseudo-random numbers
 *
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 *
 * This program 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#pragma once
#ifndef __D_RANDOM__
#define __D_RANDOM__

#include <cstdlib>

namespace DUtils {

class Random
{
public:
        static void SeedRand();
        
        static void SeedRandOnce();

        static void SeedRand(int seed);

        static void SeedRandOnce(int seed);

        template <class T>
        static T RandomValue(){
                return (T)rand()/(T)RAND_MAX;
        }

        template <class T>
        static T RandomValue(T min, T max){
                return Random::RandomValue<T>() * (max - min) + min;
        }

        static int RandomInt(int min, int max);
        
        template <class T>
        static T RandomGaussianValue(T mean, T sigma)
        {
          // Box-Muller transformation
    T x1, x2, w, y1;
    
    do {
      x1 = (T)2. * RandomValue<T>() - (T)1.;
      x2 = (T)2. * RandomValue<T>() - (T)1.;
      w = x1 * x1 + x2 * x2;
    } while ( w >= (T)1. || w == (T)0. );

    w = sqrt( ((T)-2.0 * log( w ) ) / w );
    y1 = x1 * w;

    return( mean + y1 * sigma );
        }

private:

  static bool m_seeded_current_time;
  
  static bool m_seeded_int;

};

}

#endif