Random_Stream.h

/*
 *	Copyright (c) 2015 University of Lübeck
 *
 *	Permission is hereby granted, free of charge, to any person obtaining a copy
 *	of this software and associated documentation files (the "Software"), to deal
 *	in the Software without restriction, including without limitation the rights
 *	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *	copies of the Software, and to permit persons to whom the Software is
 *	furnished to do so, subject to the following conditions:
 *
 *	The above copyright notice and this permission notice shall be included in
 *	all copies or substantial portions of the Software.
 *
 *	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 *	THE SOFTWARE.
 *
 *	AUTHORS:	Michael Schellenberger Costa: mschellenbergercosta@gmail.com
 *              Stefanie Gareis: gareis@inb.uni-luebeck.de
 */

/****************************************************************************************************/
/*                                       Random number streams                                      */
/****************************************************************************************************/
#pragma once
#include <random>

/******************************************************************************/
/*                          Class for normal distribution                     */
/******************************************************************************/
class random_stream_normal {
public:
    /* Constructors */
    explicit random_stream_normal(double mean, double stddev)
    : mt(rand()), norm_dist(mean, stddev) {}
    explicit random_stream_normal(double mean, double stddev, double seed)
    : mt(seed), norm_dist(mean, stddev) {}

    /* Overwrites the function-call operator "( )" */
    double operator() (void) {
        return norm_dist(mt);
    }
private:
    /* Random number engine: Mersenne-Twister */
    std::mt19937_64                     mt;
    /* Random number generator: Normal-distribution */
    std::normal_distribution<double>    norm_dist;
};
/******************************************************************************/
/*                                  end                                       */
/******************************************************************************/

/******************************************************************************/
/*                        Class for uniform int distribution                  */
/******************************************************************************/
class random_stream_uniform_int {
public:
    /* Constructors */
    explicit random_stream_uniform_int(double lower_bound, double upper_bound)
    : mt(rand()), uniform_dist(lower_bound, upper_bound) {}
    explicit random_stream_uniform_int(double lower_bound, double upper_bound,
                                       double seed)
    : mt(seed), uniform_dist(lower_bound, upper_bound) {}

    /* Overwrites the function-call operator "( )" */
    double operator() (void) {
        return uniform_dist(mt);
    }
private:
    /* Random number engine: Mersenne-Twister */
    std::mt19937_64                     mt;
    /* Random number generator: Uniform integer-distribution */
    std::uniform_int_distribution<>     uniform_dist;
};
/******************************************************************************/
/*                                  end                                       */
/******************************************************************************/