cachedRandom.H

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/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 2011-2015 OpenFOAM Foundation
     \\/     M anipulation  |
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.
 
    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    OpenFOAM 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 General Public License
    for more details.
 
    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
Class
    Foam::cachedRandom
 
Description
    Random number generator.
 
    Pre-computes and caches samples on construction, so that when sample01()
    is called, the function simply returns the next (pre-computed) sample. On
    reaching the last sample, the sample sequence is repeated.
 
    Constructed using a seed and sample count. If the supplied count is
    negative, no caching is performed, and a new sample is generated on each
    call to sample01().
 
    Note: the copy constructor cannot be used if count = -1.
 
SourceFiles
    cachedRandomI.H
    cachedRandom.C
    cachedRandomTemplates.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef cachedRandom_H
#define cachedRandom_H
 
#include "scalarList.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
 
// Forward declaration of classes
class cachedRandom;
 
/*---------------------------------------------------------------------------*\
                       Class cachedRandom Declaration
\*---------------------------------------------------------------------------*/
 
class cachedRandom
{
    // Private data
 
        //- Initial random number seed
        label seed_;
 
        //- List of scalar samples
        scalarList samples_;
 
        //- Current sample marker
        label sampleI_;
 
        //- Indicator, which tells if there is a stored gaussian sample
        bool hasGaussSample_;
 
        //- Stored sample value
        scalar gaussSample_;
 
 
    // Private Member Functions
 
        //- Returns the current sample
        scalar scalar01();
 
 
public:
 
    // Constructors
 
        //- Construct given seed and sample count
        cachedRandom(const label seed, const label count);
 
        //- Copy constructor with optional reset of sampleI
        cachedRandom(const cachedRandom& cr, const bool reset = false);
 
 
    // Destructor
    ~cachedRandom();
 
 
    // Member functions
 
        // Access
 
            //- Return const access to the initial random number seed
            inline label seed() const;
 
            //- Return const access to the list of samples
            inline const scalarList& samples() const;
 
            //- Return the current sample marker
            inline label sampleI() const;
 
 
        // Manipulation
 
            //- Return non-const access to the sample marker
            inline label& sampleI();
 
 
        // Evaluation
 
            // Random numbers
 
                //- Return a sample whose components lie in the range 0-1
                template<class Type>
                Type sample01();
 
                //- Return a sample whose components are normally distributed
                //  with zero mean and unity variance N(0, 1)
                template<class Type>
                Type GaussNormal();
 
                //- Return a sample between start and end
                template<class Type>
                Type position(const Type& start, const Type& end);
 
                //- Randomise value in the range 0-1
                template<class Type>
                void randomise01(Type& value);
 
 
            // Global random numbers - consistent across all processors
 
                //- Return a sample whose components lie in the range 0-1
                template<class Type>
                Type globalSample01();
 
                //- Return a sample whose components are normally distributed
                //  with zero mean and unity variance N(0, 1)
                template<class Type>
                Type globalGaussNormal();
 
                //- Return a sample between start and end
                template<class Type>
                Type globalPosition(const Type& start, const Type& end);
 
                //- Randomise value in the range 0-1
                template<class Type>
                void globalRandomise01(Type& value);
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// Template specialisations
 
template<>
scalar cachedRandom::sample01<scalar>();
 
template<>
label cachedRandom::sample01<label>();
 
template<>
scalar cachedRandom::GaussNormal<scalar>();
 
template<>
label cachedRandom::GaussNormal<label>();
 
template<>
scalar cachedRandom::position<scalar>
(
    const scalar& start,
    const scalar& end
);
 
template<>
label cachedRandom::position<label>(const label& start, const label& end);
 
template<>
scalar cachedRandom::globalSample01<scalar>();
 
template<>
label cachedRandom::globalSample01<label>();
 
template<>
scalar cachedRandom::globalGaussNormal<scalar>();
 
template<>
label cachedRandom::globalGaussNormal<label>();
 
template<>
scalar cachedRandom::globalPosition<scalar>
(
    const scalar& start,
    const scalar& end
);
 
template<>
label cachedRandom::globalPosition<label>(const label& start, const label& end);
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#include "cachedRandomI.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#ifdef NoRepository
#   include "cachedRandomTemplates.C"
#endif
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //