robinbc.cpp

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/*
* SPDX-License-Identifier: GPL-3.0-or-later
* © 2008-2024 San Diego State University Research Foundation (SDSURF).
* See LICENSE file or https://www.gnu.org/licenses/gpl-3.0.html for details. 
*/
 
/*
 * @file robinbc.cpp
 * @date 2024/10/15
 * @brief Robin Boundary Condition Class functions
 *
 */
 
#include "robinbc.h"
 
RobinBC::RobinBC(u16 k, u32 m, Real dx, Real a, Real b) {
  sp_mat A(m + 2, m + 2);
  sp_mat BG(m + 2, m + 2);
 
  A.at(0, 0) = a;
  A.at(m + 1, m + 1) = a;
 
  Gradient grad(k, m, dx);
 
  BG.row(0) = -b * grad.row(0);
  BG.row(m + 1) = b * grad.row(m);
 
  *this = A + BG;
}
 
 
RobinBC::RobinBC(u16 k, u32 m, Real dx, u32 n, Real dy, Real a, Real b) {
  RobinBC Bm(k, m, dx, a, b);
  RobinBC Bn(k, n, dy, a, b);
 
  sp_mat Im = speye(m + 2, m + 2);
  sp_mat In = speye(n + 2, n + 2);
 
  In.at(0, 0) = 0;
  In.at(n + 1, n + 1) = 0;
 
  sp_mat BC1 = Utils::spkron(In, Bm);
  sp_mat BC2 = Utils::spkron(Bn, Im);
 
  *this = BC1 + BC2;
}
 
 
RobinBC::RobinBC(u16 k, u32 m, Real dx, u32 n, Real dy, u32 o, Real dz, Real a,
                 Real b) {
  RobinBC Bm(k, m, dx, a, b);
  RobinBC Bn(k, n, dy, a, b);
  RobinBC Bo(k, o, dz, a, b);
 
  sp_mat Im = speye(m + 2, m + 2);
  sp_mat In = speye(n + 2, n + 2);
  sp_mat Io = speye(o + 2, o + 2);
 
  Io.at(0, 0) = 0;
  Io.at(o + 1, o + 1) = 0;
 
  sp_mat In2 = In;
  In2.at(0, 0) = 0;
  In2.at(n + 1, n + 1) = 0;
 
  sp_mat BC1 = Utils::spkron(Utils::spkron(Io, In2), Bm);
  sp_mat BC2 = Utils::spkron(Utils::spkron(Io, Bn), Im);
  sp_mat BC3 = Utils::spkron(Utils::spkron(Bo, In), Im);
 
  *this = BC1 + BC2 + BC3;
}