normal.H

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License
    This file is part of OpenFOAM.
 
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    the Free Software Foundation, either version 3 of the License, or
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Class
    Foam::distributions::normal
 
Description
    Normal distribution, scaled so that it spans between a specified
    minimum and maximum value, rather than from zero to infinity
 
    \f[
        PDF(x) = \frac{1}{\sigma \sqrt{2 \pi}} \\
        \exp \left( \frac{1}{2} \left( \frac{x - \mu}{\sigma} \right)^2 \right)
    \f]
 
Usage
    Example usage:
    \verbatim
    {
        type    normal;
        Q       0;
        min     0.001;
        max     0.019;
        mu      0.011;
        sigma   0.003;
    }
    \endverbatim
 
SourceFiles
    normal.C
 
See also
    Foam::distribution
 
\*---------------------------------------------------------------------------*/
 
#ifndef normal_H
#define normal_H
 
#include "unintegrable.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace distributions
{
 
/*---------------------------------------------------------------------------*\
                        Class normal Declaration
\*---------------------------------------------------------------------------*/
 
class normal
:
    public FieldDistribution<unintegrableForNonZeroQ, normal>
{
    // Private Data
 
        //- Minimum value
        const scalar min_;
 
        //- Maximum value
        const scalar max_;
 
        //- Mean
        const scalar mu_;
 
        //- Standard deviation
        const scalar sigma_;
 
        //- Constant for approximate error function and inverse error function
        static const scalar a_;
 
 
    // Private Member Functions
 
        //- Approximate error function
        static tmp<scalarField> approxErf(const scalarField& x);
 
        //- Approximate error function inverse
        static scalar approxErfInv(const scalar y);
 
        //- Return values of the un-normalised PDF for the given size exponent
        //  and x-coordinates.
        virtual tmp<scalarField> phi
        (
            const label q,
            const scalarField& x
        ) const;
 
        //- Return values of the un-normalised CDF for the given size exponent
        //  and x-coordinates.
        virtual tmp<scalarField> Phi
        (
            const label q,
            const scalarField& x
        ) const;
 
        //- Sample the distribution for zero effective size exponent
        scalar sampleForZeroQ(const scalar s) const;
 
 
public:
 
    //- Runtime type information
    TypeName("normal");
 
 
    //- Permit the multiNormal distribution to use private parts of this class
    friend class multiNormal;
 
 
    // Constructors
 
        //- Construct from a dictionary
        normal
        (
            const dictionary& dict,
            Random& rndGen,
            const label sampleQ
        );
 
        //- Construct from components
        normal
        (
            Random& rndGen,
            const label Q,
            const label sampleQ,
            const label n,
            const scalar min,
            const scalar max,
            const scalar mu,
            const scalar sigma
        );
 
        //- Construct copy
        normal(const normal& d, const label sampleQ);
 
        //- Construct and return a clone
        virtual autoPtr<distribution> clone(const label sampleQ) const
        {
            return autoPtr<distribution>(new normal(*this, sampleQ));
        }
 
 
    //- Destructor
    virtual ~normal();
 
 
    // Member Functions
 
        //- Sample the distribution
        virtual scalar sample() const;
 
        //- Sample the distribution
        using FieldDistribution<unintegrableForNonZeroQ, normal>::sample;
 
        //- Return the minimum value
        virtual scalar min() const;
 
        //- Return the maximum value
        virtual scalar max() const;
 
        //- Return the mean value
        virtual scalar mean() const;
 
        //- Return coordinates to plot across the range of the distribution
        virtual tmp<scalarField> x(const label n) const;
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace distributions
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //