robinbc.cpp

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#include "robinbc.h"
 
// 1-D Constructor
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;
}
 
// 2-D Constructor
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;
}
 
// 3-D Constructor
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;
}