Random.h

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/*--------------------------------------------------------------------------------------------
Copyright (c) 2019, NDEVR LLC
tyler.parke@ndevr.org
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Subject to the terms of the Enterprise+ Agreement, NDEVR hereby grants 
Licensee a limited, non-exclusive, non-transferable, royalty-free license 
(without the right to sublicense) to use the API solely for the purpose of 
Licensee's internal development efforts to develop applications for which 
the API was provided.
 
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.
 
Library: Base
File: Random
Included in API: True
Author(s): Tyler Parke
 *-----------------------------------------------------------------------------------------**/
#pragma once
#include <NDEVR/BaseValues.h>
#include <random>
namespace NDEVR
{
    /**--------------------------------------------------------------------------------------------------
    \brief Dummy class for including random number generator functions
    **/
    class Random
    {};
    /**--------------------------------------------------------------------------------------------------
        \brief Returns a pseudo-random number between 0 and the associated max value
    
    Author: Tyler Parke
    
    Date: 2017-11-18
    
    Parameters:
    max -  The maximum value the random value can take on.
    
    \returns A pseudo-random number.
    **/
    template<class t_type>
    t_type MakeRandom(t_type max)
    {
        static std::mt19937 rng(rand());
        std::uniform_int_distribution<t_type> gen(0, max);
        return gen(rng);
    };
 
    /**--------------------------------------------------------------------------------------------------
        Returns a pseudo-random number between 0 and the associated max value
    
    Author: Tyler Parke
    
    Date: 2017-11-18
    
    Parameters:
    max -  The maximum value the random value can take on.
    
    \returns A pseudo-random number.
    **/
    template<>
    inline fltp04 MakeRandom(fltp04 max)
    {
        return (max * cast<fltp04>(MakeRandom<uint02>(Constant<uint02>::Max))) / Constant<uint02>::Max;
    };
    
 
    /**--------------------------------------------------------------------------------------------------
        \brief Returns a pseudo-random number between 0 and the associated max value
    
    Author: Tyler Parke
    
    Date: 2017-11-18
    
    Parameters:
    max -  The maximum value the random value can take on.
    
    \returns A pseudo-random number.
    **/
    template<>
    inline fltp08 MakeRandom(fltp08 max)
    {
        return (max * MakeRandom<uint04>(Constant<uint04>::Max)) / cast<fltp08>(Constant<uint04>::Max);
    }
 
    /**--------------------------------------------------------------------------------------------------
        \brief Returns a pseudo-random number between 0 and the associated max value
    
    Author: Tyler Parke
    
    Date: 2017-11-18
    
    Parameters:
    max -  The maximum value the random value can take on.
    min -  The maximum value the random value can take on.
    \returns A pseudo-random number.
    **/
 
    template<class t_type>
    t_type MakeRandom(t_type min, t_type max)
    {
        lib_assert(min <= max, "Random generation min value must be less than or equal to max");
        return cast<t_type>(MakeRandom<fltp08>(cast<fltp08>(max - min))) + min;
    };
    /**--------------------------------------------------------------------------------------------------
    \brief Used to generate a random number over a Gaussian distribution with templated setup parameters
        for very quick speed.
    **/
    template<sint04 ia = 16807, sint04 im = 2147483647, sint04 iq = 127773, sint04 ir = 2836, sint04 ntab = 32>
    class GaussianRN
    {
    public:
        GaussianRN(sint08 didum) 
            : idum(didum)
            , eps(1.2e-7)
        {}
        fltp08 gasdev()
        {
            return gasdev(idum);
        }
    protected:
        fltp08 ran1(sint08& idum)
        {
            fltp08 am = 1.0 / im;
            fltp08 ntiv = (1 + (im - 1) / ntab);
            sint04 j;
            sint08 k;
            static sint08 iy = 0;
            static sint08 iv[ntab];
            fltp08 temp;
 
            if (idum <= 0 || !iy) 
            {
                if (-idum < 1) 
                    idum = 1;
                else 
                    idum = -(idum);
                for (j = ntab + 7; j >= 0; j--) 
                {
                    k = (idum) / iq;
                    idum = ia * (idum - k * iq) - ir * k;
                    if (idum < 0) 
                        idum += im;
                    if (j < ntab) 
                        iv[j] = idum;
                }
                iy = iv[0];
            }
            k = (idum) / iq;
            idum = ia * (idum - k * iq) - ir * k;
            if (idum < 0) 
                idum += im;
            j = iy / ntiv;
            iy = iv[j];
            iv[j] = idum;
            if ((temp = am * iy) > 1 - eps) 
                return eps;
            else 
                return temp;
        }
        fltp08 gasdev(sint08& idum)
        {
            static sint08 iset = 0;
            static fltp08 gset;
            double fac, rsq, v1, v2;
 
            if (iset == 0) 
            {
                do 
                {
                    v1 = 2.0 * ran1(idum) - 1.0;
                    v2 = 2.0 * ran1(idum) - 1.0;
                    rsq = v1*v1 + v2 * v2;
                } 
                while (rsq >= 1.0 || rsq == 0.0);
 
                fac = sqrt(-2.0 * log(rsq) / rsq);
                gset = v1 * fac;
                iset = 1;
                return v2 * fac;
            }
            else 
            {
                iset = 0;
                return gset;
            }
        }
    private:
        sint08 idum;
        fltp08 eps;
        GaussianRN(const GaussianRN& rhs) = delete;
        const GaussianRN &operator=(const GaussianRN& rhs) = delete;
    };
 
 
 
}