modified_maxwell_3d_double_layer_operators_kernel_functor.hpp

// Copyright (C) 2011-2012 by the BEM++ Authors
//
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// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
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#ifndef fiber_modified_maxwell_3d_double_layer_operators_kernel_functor_hpp
#define fiber_modified_maxwell_3d_double_layer_operators_kernel_functor_hpp

#include "../common/common.hpp"
#include "../common/complex_aux.hpp"

#include "geometrical_data.hpp"
#include "scalar_traits.hpp"

#include "modified_helmholtz_3d_single_layer_potential_kernel_functor.hpp"

namespace Fiber
{

template <typename ValueType_>
class ModifiedMaxwell3dDoubleLayerOperatorsKernelFunctor
{
public:
    typedef ValueType_ ValueType;
    typedef typename ScalarTraits<ValueType>::RealType CoordinateType;

    explicit ModifiedMaxwell3dDoubleLayerOperatorsKernelFunctor(
            ValueType waveNumber) :
        m_waveNumber(waveNumber)
    {}

    int kernelCount() const { return 1; }
    int kernelRowCount(int /* kernelIndex */) const { return 3; }
    int kernelColCount(int /* kernelIndex */) const { return 1; }

    void addGeometricalDependencies(size_t& testGeomDeps, size_t& trialGeomDeps) const {
        testGeomDeps |= GLOBALS;
        trialGeomDeps |= GLOBALS;
    }

    ValueType waveNumber() const { return m_waveNumber; }

    template <template <typename T> class CollectionOf2dSlicesOfNdArrays>
    void evaluate(
            const ConstGeometricalDataSlice<CoordinateType>& testGeomData,
            const ConstGeometricalDataSlice<CoordinateType>& trialGeomData,
            CollectionOf2dSlicesOfNdArrays<ValueType>& result) const {
        const int coordCount = 3;

        CoordinateType distanceSq = 0;
        for (int coordIndex = 0; coordIndex < coordCount; ++coordIndex) {
            CoordinateType diff = testGeomData.global(coordIndex) -
                    trialGeomData.global(coordIndex);
            distanceSq += diff * diff;
        }
        const CoordinateType distance = sqrt(distanceSq);
        const ValueType commonFactor =
            static_cast<CoordinateType>(-1. / (4. * M_PI)) *
            (static_cast<CoordinateType>(1.) + m_waveNumber * distance) /
            (distance * distanceSq) *
            exp(-m_waveNumber * distance);
        for (int coordIndex = 0; coordIndex < coordCount; ++coordIndex)
            result[0](coordIndex, 0) = commonFactor *
                (testGeomData.global(coordIndex) -
                 trialGeomData.global(coordIndex));
    }

    CoordinateType estimateRelativeScale(CoordinateType distance) const {
        return exp(-realPart(m_waveNumber) * distance);
    }

private:
    ValueType m_waveNumber;
};

} // namespace Fiber

#endif