third-order.cc (Latest change: Author:Lakshman Anumolu <acrlakshman@yahoo.co.in>, 2019-06-22 16:11:09 -0500, [commit: 6586b7c])

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// Copyright 2019 Lakshman Anumolu, Raunak Bardia.
//
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#include "gals/cpu/gradient/third-order.h"

template <typename T, typename T_GRID>
GALS::CPU::ThirdOrder<T, T_GRID>::ThirdOrder()
{
}

template <typename T, typename T_GRID>
GALS::CPU::ThirdOrder<T, T_GRID>::~ThirdOrder()
{
}

template <typename T, typename T_GRID>
void GALS::CPU::ThirdOrder<T, T_GRID>::compute(const Array<T_GRID, T> &alpha, Array<T_GRID, Vec3<T>> &grad_alpha)
{
  const Vec3<int> num_cells = alpha.numCells();
  const T_GRID &grid = alpha.grid();
  const Vec3<typename T_GRID::value_type> dx = grid.dX();
  const auto &axis_vectors = GALS::CPU::Grid<typename T_GRID::value_type, T_GRID::dim>::axis_vectors;

  for (int i = 0; i < num_cells[0]; ++i)
    for (int j = 0; j < num_cells[1]; ++j)
      for (int k = 0; k < num_cells[2]; ++k) {
        for (int axis = 0; axis < T_GRID::dim; ++axis) {
          typename T_GRID::value_type one_by_dx = static_cast<typename T_GRID::value_type>(1.) / (6.0 * dx[axis]);

          grad_alpha(i, j, k)[axis] =
              (2 * alpha(i + axis_vectors(axis, 0), j + axis_vectors(axis, 1), k + axis_vectors(axis, 2)) +
               3 * alpha(i, j, k) -
               6 * alpha(i - axis_vectors(axis, 0), j - axis_vectors(axis, 1), k - axis_vectors(axis, 2)) +
               1 * alpha(i - 2 * axis_vectors(axis, 0), j - 2 * axis_vectors(axis, 1), k - 2 * axis_vectors(axis, 2))) *
              one_by_dx;
        }
      }
}

template <typename T, typename T_GRID>
void GALS::CPU::ThirdOrder<T, T_GRID>::compute(const Array<T_GRID, Vec3<T>> &alpha, Array<T_GRID, Mat3<T>> &grad_alpha)
{
  const Vec3<int> num_cells = alpha.numCells();
  const T_GRID &grid = alpha.grid();
  const Vec3<typename T_GRID::value_type> dx = grid.dX();
  const auto &axis_vectors = GALS::CPU::Grid<typename T_GRID::value_type, T_GRID::dim>::axis_vectors;

  for (int i = 0; i < num_cells[0]; ++i)
    for (int j = 0; j < num_cells[1]; ++j)
      for (int k = 0; k < num_cells[2]; ++k) {
        for (int axis = 0; axis < T_GRID::dim; ++axis) {
          for (int cmpt = 0; cmpt < T_GRID::dim; ++cmpt) {
            typename T_GRID::value_type one_by_dx = static_cast<typename T_GRID::value_type>(1.) / (6 * dx[cmpt]);

            grad_alpha(i, j, k)(axis, cmpt) =
                (2 * alpha(i + axis_vectors(axis, 0), j + axis_vectors(axis, 1), k + axis_vectors(axis, 2))[axis] +
                 3 * alpha(i, j, k)[axis] -
                 6 * alpha(i - axis_vectors(axis, 0), j - axis_vectors(axis, 1), k - axis_vectors(axis, 2))[axis] +
                 1 * alpha(i - 2 * axis_vectors(axis, 0), j - 2 * axis_vectors(axis, 1),
                           k - 2 * axis_vectors(axis, 2))[axis]) *
                one_by_dx;
          }
        }
      }
}

template class GALS::CPU::ThirdOrder<double, GALS::CPU::Grid<double, 1>>;
template class GALS::CPU::ThirdOrder<double, GALS::CPU::Grid<double, 2>>;
template class GALS::CPU::ThirdOrder<double, GALS::CPU::Grid<double, 3>>;