Function AverageAndPackVectorField

Source/Diagnostics/FieldIO.cpp:156–190

\brief Takes an array of 3 MultiFab `vector_field` * (representing the x, y, z components of a vector), * averages it to the cell center, and stores the * resulting MultiFab in mf_avg (in the components dcomp to dcomp+2) * Should only be used for BTD now. */

 * Should only be used for BTD now.
 */
void
AverageAndPackVectorField( MultiFab& mf_avg,
                           const std::array< std::unique_ptr<MultiFab>, 3 >& vector_field,
                           const DistributionMapping& dm,
                           const int dcomp, const IntVect ngrow )
{
#ifndef WARPX_DIM_RZ
    (void)dm;
#endif

#ifdef WARPX_DIM_RZ
    // Note that vector_total is declared in the same way as
    // vector_field so that it can be handled the same way.
    std::array<std::unique_ptr<MultiFab>,3> vector_total;
    if (vector_field[0]->nComp() > 1) {
        // With the RZ solver, if there are more than one component, the total
        // fields needs to be constructed in temporary MultiFabs.
        vector_total[0] = std::make_unique<MultiFab>(vector_field[0]->boxArray(), dm, 1, vector_field[0]->nGrowVect());
        vector_total[1] = std::make_unique<MultiFab>(vector_field[1]->boxArray(), dm, 1, vector_field[1]->nGrowVect());
        vector_total[2] = std::make_unique<MultiFab>(vector_field[2]->boxArray(), dm, 1, vector_field[2]->nGrowVect());
        ConstructTotalRZVectorField(vector_total, vector_field);
    } else {
        // Create aliases of the MultiFabs
        vector_total[0] = std::make_unique<MultiFab>(*vector_field[0], amrex::make_alias, 0, 1);
        vector_total[1] = std::make_unique<MultiFab>(*vector_field[1], amrex::make_alias, 0, 1);
        vector_total[2] = std::make_unique<MultiFab>(*vector_field[2], amrex::make_alias, 0, 1);
    }
#else
    const std::array<std::unique_ptr<MultiFab>,3> &vector_total = vector_field;
#endif

    ablastr::coarsen::sample::Coarsen(mf_avg, *(vector_total[0]), dcomp  , 0, 1, ngrow );
    ablastr::coarsen::sample::Coarsen(mf_avg, *(vector_total[1]), dcomp + 1, 0, 1, ngrow );
    ablastr::coarsen::sample::Coarsen(mf_avg, *(vector_total[2]), dcomp + 2, 0, 1, ngrow );
}

/** \brief Take a MultiFab `scalar_field`
 * averages it to the cell center, and stores the