Hanning.C

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    Copyright (C) 2016-2020 OpenCFD Ltd.
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License
    This file is part of OpenFOAM.
 
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#include "Hanning.H"
#include "addToRunTimeSelectionTable.H"
#include "mathematicalConstants.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace windowModels
{
 
// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
defineTypeNameAndDebug(Hanning, 0);
addToRunTimeSelectionTable(windowModel, Hanning, dictionary);
 
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
Hanning::Hanning(const dictionary& dict, const label nSamples)
:
    windowModel(dict, nSamples),
    symmetric_(dict.get<bool>("symmetric")),
    extended_(dict.get<bool>("extended")),
    alpha_(dict.getOrDefault<scalar>("alpha", 0.5))  // Hamming = 0.54
{
    // Extend range if required
    const label offset = extended_ ? 1 : 0;
    const scalar m = nSamples - 1 + 2*offset;
 
    scalarField t(nSamples);
    forAll(t, i)
    {
        t[i] = i + offset;
    }
 
    scalarField& wf = *this;
    wf = alpha_ - (1 - alpha_)*cos(constant::mathematical::twoPi*t/m);
 
    // Reset second half of window if symmetric
    if (symmetric_)
    {
        label midPointI = 0;
        if (nSamples % 2 == 0)
        {
            midPointI = nSamples/2;
        }
        else
        {
            midPointI = (nSamples + 1)/2;
        }
 
        for (label i = 0; i < midPointI; i++)
        {
            wf[nSamples - i - 1] = wf[i];
        }
    }
 
    const scalar sumSqr = sum(sqr(wf));
 
    // Normalisation
    wf *= sqrt(nSamples/sumSqr);
}
 
 
// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
bool Hanning::symmetric() const
{
    return symmetric_;
}
 
 
bool Hanning::extended() const
{
    return extended_;
}
 
 
Foam::scalar Hanning::alpha() const
{
    return alpha_;
}
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace windowModels
} // End namespace Foam
 
// ************************************************************************* //