laplace-potential-gradient/laplace_3d_single_layer_potential_gradient_kernel_functor.hpp at master · wsmigaj/laplace-potential-gradient · GitHub

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// Copyright (C) 2016 by Wojciech Smigaj.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#ifndef fiber_laplace_3d_single_layer_potential_gradient_kernel_functor_hpp
#define fiber_laplace_3d_single_layer_potential_gradient_kernel_functor_hpp

#include "common/common.hpp"

#include "fiber/geometrical_data.hpp"
#include "fiber/scalar_traits.hpp"

namespace Fiber
{

/** \ingroup laplace_3d
 *  \ingroup functors
 *  \brief Gradient of the single-layer-potential kernel functor for the
 *  Laplace equation in 3D.
 *
 *  \tparam ValueType Type used to represent the values of the kernel. It can
 *  be one of: \c float, \c double, <tt>std::complex<float></tt> and
 *  <tt>std::complex<double></tt>.
 *
 *  \see laplace_3d
 */

template <typename ValueType_>
class Laplace3dSingleLayerPotentialGradientKernelFunctor
{
public:
    typedef ValueType_ ValueType;
    typedef typename ScalarTraits<ValueType>::RealType CoordinateType;

    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;
    }

    template <template <typename T> class CollectionOf2dSlicesOfNdArrays>
    void evaluate(
            const ConstGeometricalDataSlice<CoordinateType>& testGeomData,
            const ConstGeometricalDataSlice<CoordinateType>& trialGeomData,
            CollectionOf2dSlicesOfNdArrays<ValueType>& result) const {
        const int coordCount = 3;
        assert(testGeomData.dimWorld() == coordCount);
        assert(result.size() == 1);

        ValueType dist2 = 0;
        ValueType diffs[coordCount];
        for (int coordIndex = 0; coordIndex < coordCount; ++coordIndex) {
            ValueType diff = testGeomData.global(coordIndex) -
                    trialGeomData.global(coordIndex);
            diffs[coordIndex] = diff;
            dist2 += diff * diff;
        }
        const ValueType commonFactor =
            static_cast<CoordinateType>(-1. / (4. * M_PI)) / (dist2 * sqrt(dist2));
        for (int coordIndex = 0; coordIndex < coordCount; ++coordIndex) {
            result[0](coordIndex, 0) = diffs[coordIndex] * commonFactor;
        }
    }
};

} // namespace Fiber

#endif