common.cpp

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/*
 * Copyright (C) 2010-2024 The ESPResSo project
 * Copyright (C) 2002,2003,2004,2005,2006,2007,2008,2009,2010
 *   Max-Planck-Institute for Polymer Research, Theory Group
 *
 * This file is part of ESPResSo.
 *
 * ESPResSo is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * ESPResSo is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include <config/config.hpp>
 
#if defined(ESPRESSO_P3M) or defined(ESPRESSO_DP3M)
 
#include "common.hpp"
 
#include "LocalBox.hpp"
 
#include <utils/Vector.hpp>
 
#include <cmath>
 
void P3MLocalMesh::calc_local_ca_mesh(P3MParameters const &params,
                                      LocalBox const &local_geo, double skin,
                                      double space_layer) {
  int i;
  int ind[3];
  // total skin size
  auto const full_skin = Utils::Vector3d{params.cao_cut} +
                         Utils::Vector3d::broadcast(skin) +
                         Utils::Vector3d{0., 0., space_layer};
  // inner left down corner
  auto const &inner_ld_pos = local_geo.my_left();
  // inner up right corner
  auto const &inner_ur_pos = local_geo.my_right();
  // outer up right corner
  auto const outer_ur_pos = inner_ur_pos + full_skin;
  // outer left down corner
  auto const outer_ld_pos = inner_ld_pos - full_skin;
  // convert spatial positions to grid positions
  auto const inner_ld_grid_pos = params.calc_grid_pos(inner_ld_pos);
  auto const inner_ur_grid_pos = params.calc_grid_pos(inner_ur_pos);
  auto const outer_ld_grid_pos = params.calc_grid_pos(outer_ld_pos);
  auto const outer_ur_grid_pos = params.calc_grid_pos(outer_ur_pos);
 
  /* inner left down grid point (global index) */
  for (i = 0; i < 3; i++)
    in_ld[i] = static_cast<int>(std::ceil(inner_ld_grid_pos[i]));
  /* inner up right grid point (global index) */
  for (i = 0; i < 3; i++)
    in_ur[i] = static_cast<int>(std::floor(inner_ur_grid_pos[i]));
 
  /* correct roundoff errors at boundary */
  for (i = 0; i < 3; i++) {
    if (inner_ur_grid_pos[i] - in_ur[i] < round_error_prec)
      in_ur[i]--;
    if (inner_ld_grid_pos[i] - in_ld[i] + 1. < round_error_prec)
      in_ld[i]--;
  }
  /* inner grid dimensions */
  for (i = 0; i < 3; i++)
    inner[i] = in_ur[i] - in_ld[i] + 1;
  /* index of left down grid point in global mesh */
  for (i = 0; i < 3; i++)
    ld_ind[i] = static_cast<int>(std::ceil(outer_ld_grid_pos[i]));
  /* left down margin */
  for (i = 0; i < 3; i++)
    margin[i * 2] = in_ld[i] - ld_ind[i];
  /* up right grid point */
  for (i = 0; i < 3; i++)
    ind[i] = static_cast<int>(std::floor(outer_ur_grid_pos[i]));
  /* correct roundoff errors at up right boundary */
  for (i = 0; i < 3; i++)
    if (outer_ur_grid_pos[i] - ind[i] == 0.)
      ind[i]--;
  /* up right margin */
  for (i = 0; i < 3; i++)
    margin[(i * 2) + 1] = ind[i] - in_ur[i];
 
  /* grid dimension */
  size = 1ull;
  for (i = 0; i < 3; i++) {
    dim[i] = ind[i] - ld_ind[i] + 1;
    size *= static_cast<std::size_t>(dim[i]);
  }
 
  /* reduce inner grid indices from global to local */
  for (i = 0; i < 3; i++)
    in_ld[i] = margin[i * 2];
  for (i = 0; i < 3; i++)
    in_ur[i] = margin[i * 2] + inner[i];
 
  q_2_off = dim[2] - params.cao;
  q_21_off = dim[2] * (dim[1] - params.cao);
 
  n_halo_ld = {margin[0], margin[2], margin[4]};
  n_halo_ur = {margin[1], margin[3], margin[5]};
  ld_no_halo = Utils::Vector3i(ld_ind) + n_halo_ld;
  ur_no_halo = ld_no_halo + dim - n_halo_ld - n_halo_ur;
  dim_no_halo = ur_no_halo - ld_no_halo;
}
 
#endif // defined(ESPRESSO_P3M) or defined(ESPRESSO_DP3M)