// ============================================================================
void GetNeighboursCartesian3d(const int i,
const int nx, const int ny, const int nz,
int& left, int& right, int& lower, int& upper,
int& below, int& above)
{
int ixy, iz;
ixy = i % (nx * ny);
iz = (i - ixy) / (nx * ny);
if (iz == 0) below = -1;
else below = i - nx * ny;
if (iz == nz - 1) above = -1;
else above = i + nx * ny;
GetNeighboursCartesian2d(ixy, nx, ny, left, right, lower, upper);
if (left != -1) left += iz * (nx * ny);
if (right != -1) right += iz * (nx * ny);
if (lower != -1) lower += iz * (nx * ny);
if (upper != -1) upper += iz * (nx * ny);
}
std::pair< Teuchos::RCP<Matrix>, Teuchos::RCP<Matrix> >
Cross2D_Helmholtz_Pair(const Teuchos::RCP<const Map> & map,
const GlobalOrdinal nx, const GlobalOrdinal ny,
const double h, const double delta,
const int PMLgridptsx_left, const int PMLgridptsx_right,
const int PMLgridptsy_left, const int PMLgridptsy_right,
const double omega, const Scalar shift,
const int model) {
Teuchos::RCP<Matrix> ktx = MatrixTraits<Map,Matrix>::Build(map, 5);
Teuchos::RCP<Matrix> mtx = MatrixTraits<Map,Matrix>::Build(map, 1);
LocalOrdinal NumMyElements = map->getNodeNumElements();
Teuchos::ArrayView<const GlobalOrdinal> MyGlobalElements = map->getNodeElementList();
GlobalOrdinal left, right, lower, upper, center;
LocalOrdinal nnz=5;
std::vector<Scalar> Values(nnz);
std::vector<GlobalOrdinal> Indices(nnz);
VelocityModel<Scalar,LocalOrdinal,GlobalOrdinal> velocitymodel(2,model);
double LBx, RBx, LBy, RBy, Dx, Dy;
Scalar sx_left, sx_center, sx_right;
Scalar sy_left, sy_center, sy_right;
Scalar c;
// Calculate some parameters
Dx = ((double) nx-1)*h;
Dy = ((double) ny-1)*h;
LBx = ((double) PMLgridptsx_left)*h;
RBx = Dx-((double) PMLgridptsx_right)*h;
LBy = ((double) PMLgridptsy_left)*h;
RBy = Dy-((double) PMLgridptsy_right)*h;
for (LocalOrdinal i = 0; i < NumMyElements; ++i) {
// calculate PML functions
size_t numEntries = 0;
center = MyGlobalElements[i];
GetNeighboursCartesian2d(center, nx, ny, left, right, lower, upper);
GetPMLvalues(center, nx, ny, h, delta,
Dx, Dy, LBx, RBx, LBy, RBy,
sx_left, sx_center, sx_right,
sy_left, sy_center, sy_right);
// get velocity
GlobalOrdinal ix, iy;
ix = i % nx;
iy = (i - ix) / nx;
double xcoord, ycoord;
xcoord=((double) ix)*h;
ycoord=((double) iy)*h;
c = velocitymodel.getVelocity(xcoord,ycoord,0.0);
if (left != -1) {
Indices[numEntries] = left;
Values [numEntries] = -(sy_center/sx_center + sy_center/sx_left)/2.0;
numEntries++;
}
if (right != -1) {
Indices[numEntries] = right;
Values [numEntries] = -(sy_center/sx_center + sy_center/sx_right)/2.0;
numEntries++;
}
if (lower != -1) {
Indices[numEntries] = lower;
Values [numEntries] = -(sx_center/sy_center + sx_center/sy_left)/2.0;
numEntries++;
}
if (upper != -1) {
Indices[numEntries] = upper;
Values [numEntries] = -(sx_center/sy_center + sx_center/sy_right)/2.0;
numEntries++;
}
// diagonal
Scalar z = (Scalar) 0.0;
for (size_t j = 0; j < numEntries; j++)
z -= Values[j];
Indices[numEntries] = center;
Values [numEntries] = z;
numEntries++;
Teuchos::ArrayView<GlobalOrdinal> iv(&Indices[0], numEntries);
Teuchos::ArrayView<Scalar> av(&Values[0], numEntries);
ktx->insertGlobalValues(center, iv, av);
mtx->insertGlobalValues(center,
Teuchos::tuple<GlobalOrdinal>(center),
Teuchos::tuple<Scalar>(h*h*sx_center*sy_center/(c*c)) );
}
ktx->fillComplete();
mtx->fillComplete();
std::pair< Teuchos::RCP<Matrix>, Teuchos::RCP<Matrix> > system;
system=std::make_pair(ktx,mtx);
return system;
} //Cross2D_Helmholtz
