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========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Copyright (C) 2024 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/>.
\*---------------------------------------------------------------------------*/
#include "standardNormal.H"
#include "mathematicalConstants.H"
#include "addToRunTimeSelectionTable.H"
// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
namespace Foam
{
namespace distributions
{
defineTypeNameAndDebug(standardNormal, 0);
}
}
const Foam::scalar Foam::distributions::standardNormal::a_ = 0.147;
using namespace Foam::constant::mathematical;
// * * * * * * * * * * * * * Static Member Functions * * * * * * * * * * * * //
Foam::tmp<Foam::scalarField> Foam::distributions::standardNormal::approxErf
(
const scalarField& x
)
{
return sign(x)*sqrt(1 - exp(-sqr(x)*(4/pi + a_*sqr(x))/(1 + a_*sqr(x))));
}
Foam::scalar Foam::distributions::standardNormal::approxErfInv(const scalar y)
{
const scalar l = log(Foam::max(1 - y*y, small/2)), b = 2/(pi*a_) + l/2;
return sign(y)*sqrt(-b + sqrt(b*b - l/a_));
}
// * * * * * * * * * * * * * * * * Constructors * * * * * * * * * * * * * * //
Foam::distributions::standardNormal::standardNormal(randomGenerator&& rndGen)
:
FieldDistribution<distribution, standardNormal>(0, 0, std::move(rndGen))
{}
Foam::distributions::standardNormal::standardNormal
(
const randomGenerator::seed& s,
const bool global
)
:
standardNormal(randomGenerator(s, global))
{}
Foam::distributions::standardNormal::standardNormal(const standardNormal& d)
:
FieldDistribution<distribution, standardNormal>(d, 0)
{}
// * * * * * * * * * * * * * * * * Destructor * * * * * * * * * * * * * * * //
Foam::distributions::standardNormal::~standardNormal()
{}
// * * * * * * * * * * * * * * * Member Functions * * * * * * * * * * * * * //
Foam::scalar Foam::distributions::standardNormal::sample() const
{
static const scalar sqrt2 = sqrt(scalar(2));
const scalar s = rndGen_.sample01<scalar>();
return approxErfInv(2*s - 1)*sqrt2;
}
Foam::scalar Foam::distributions::standardNormal::min() const
{
return -vGreat;
}
Foam::scalar Foam::distributions::standardNormal::max() const
{
return vGreat;
}
Foam::scalar Foam::distributions::standardNormal::mean() const
{
return 0;
}
Foam::tmp<Foam::scalarField>
Foam::distributions::standardNormal::integralPDFxPow
(
const scalarField& x,
const label e,
const bool
) const
{
if (e != 0) NotImplemented;
static const scalar sqrt2 = sqrt(scalar(2));
return (1 + approxErf(x/sqrt2))/2;
}
Foam::tmp<Foam::scalarField>
Foam::distributions::standardNormal::plotX(const label n) const
{
const scalar x0 = approxErfInv(1 - rootSmall);
const scalar x1 = approxErfInv(rootSmall - 1);
tmp<scalarField> tResult(new scalarField(n));
scalarField& result = tResult.ref();
forAll(result, i)
{
const scalar f = scalar(i)/(n - 1);
result[i] = (1 - f)*x0 + f*x1;
}
return tResult;
}
Foam::tmp<Foam::scalarField> Foam::distributions::standardNormal::plotPDF
(
const scalarField& x
) const
{
static const scalar sqrt2Pi = sqrt(2*pi);
return exp(- sqr(x)/2)/sqrt2Pi;
}
// ************************************************************************* //
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