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/* Copyright 2019 Edoardo Zoni
*
* This file is part of WarpX.
*
* License: BSD-3-Clause-LBNL
*/
#include "SpectralBaseAlgorithm.H"
#include <cmath>
using namespace amrex;
/**
* \brief Compute spectral divergence of E
*/
void
SpectralBaseAlgorithm::ComputeSpectralDivE (
const int lev,
SpectralFieldData& field_data,
const std::array<std::unique_ptr<amrex::MultiFab>,3>& Efield,
amrex::MultiFab& divE )
{
using Idx = SpectralFieldIndex;
// Forward Fourier transform of E
field_data.ForwardTransform(lev, *Efield[0], Idx::Ex, 0 );
field_data.ForwardTransform(lev, *Efield[1], Idx::Ey, 0 );
field_data.ForwardTransform(lev, *Efield[2], Idx::Ez, 0 );
// Loop over boxes
for (MFIter mfi(field_data.fields); mfi.isValid(); ++mfi){
const Box& bx = field_data.fields[mfi].box();
// Extract arrays for the fields to be updated
Array4<Complex> fields = field_data.fields[mfi].array();
// Extract pointers for the k vectors
const Real* modified_kx_arr = modified_kx_vec[mfi].dataPtr();
#if (AMREX_SPACEDIM==3)
const Real* modified_ky_arr = modified_ky_vec[mfi].dataPtr();
#endif
const Real* modified_kz_arr = modified_kz_vec[mfi].dataPtr();
// Loop over indices within one box
ParallelFor(bx,
[=] AMREX_GPU_DEVICE(int i, int j, int k) noexcept
{
// Shortcuts for the components of E
const Complex Ex = fields(i,j,k,Idx::Ex);
const Complex Ey = fields(i,j,k,Idx::Ey);
const Complex Ez = fields(i,j,k,Idx::Ez);
// k vector values
const Real kx = modified_kx_arr[i];
#if (AMREX_SPACEDIM==3)
const Real ky = modified_ky_arr[j];
const Real kz = modified_kz_arr[k];
#else
constexpr Real ky = 0;
const Real kz = modified_kz_arr[j];
#endif
const Complex I = Complex{0,1};
// div(E) in Fourier space
fields(i,j,k,Idx::divE) = I*(kx*Ex+ky*Ey+kz*Ez);
});
}
// Backward Fourier transform
field_data.BackwardTransform(lev, divE, Idx::divE, 0 );
}
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