Method grad

ibtk/src/math/PatchMathOps.cpp:2987–3124

} // div

void
PatchMathOps::grad(Pointer<CellData<NDIM, double>> dst,
                   const double alpha,
                   const Pointer<CellData<NDIM, double>> src1,
                   const double beta,
                   const Pointer<CellData<NDIM, double>> src2,
                   const Pointer<Patch<NDIM>> patch,
                   const int l) const
{
    const Pointer<CartesianPatchGeometry<NDIM>> pgeom = patch->getPatchGeometry();
    const double* const dx = pgeom->getDx();

    double* const G = dst->getPointer();
    const int G_ghosts = (dst->getGhostCellWidth()).max();

    const double* const U = src1->getPointer(l);
    const int U_ghosts = (src1->getGhostCellWidth()).max();

    const Box<NDIM>& patch_box = patch->getBox();

#if !defined(NDEBUG)
    if (G_ghosts != (dst->getGhostCellWidth()).min())
    {
        TBOX_ERROR("PatchMathOps::grad():\n"
                   << "  dst does not have uniform ghost cell widths" << std::endl);
    }

    const int G_depth = dst->getDepth();

    if (G_depth != NDIM)
    {
        TBOX_ERROR("PatchMathOps::grad():\n"
                   << "  dst has incorrect depth" << std::endl);
    }

    if (U_ghosts != (src1->getGhostCellWidth()).min())
    {
        TBOX_ERROR("PatchMathOps::grad():\n"
                   << "  src1 does not have uniform ghost cell widths" << std::endl);
    }

    if (src1 == dst)
    {
        TBOX_ERROR("PatchMathOps::grad():\n"
                   << "  src1 == dst." << std::endl);
    }

    if ((src1 == src2) && (beta != 0.0))
    {
        TBOX_ERROR("PatchMathOps::grad():\n"
                   << "  src1 == src2 but beta is nonzero." << std::endl);
    }

    const Box<NDIM>& U_box = src1->getGhostBox();
    const Box<NDIM> U_box_shrunk = Box<NDIM>::grow(U_box, -1);

    if ((!U_box_shrunk.contains(patch_box.lower())) || (!U_box_shrunk.contains(patch_box.upper())))
    {