void SGSSmoother( VT &sol, const MT &M, VT &def )
// backward Gauss-Seidel
// result in sol_vec; def_vec: correct defect before call, after call destroyed
{
typename VT::Iterator viter(def);
typename VT::RevIterator vReviter(def);
typename VT::VectorEntry row, col;
typename MT::MatrixEntry me;
register double sum, diag;
int row_index;
/* symmetric Gauss-Seidel */
while(viter(row))
{
typename MT::Iterator miter(M,row);
row_index = row.GetIndex();
sum = def[row];
miter(me);
diag = M[me];
while(miter(me))
{
col = me.dest();
if( col.GetIndex() < row_index )
sum -= M[me] * def[col];
}
def[row] = sum / diag;
}
viter.reset();
while(viter(row))
def[row] *= M.DiagValue(row);
while(vReviter(row))
{
typename MT::Iterator miter(M,row);
row_index = row.GetIndex();
sum = def[row];
miter(me);
diag = M[me];
while(miter(me))
{
col = me.dest();
if( col.GetIndex() > row_index )
sum -= M[me] * def[col];
}
def[row] = sum / diag;
}
sol += def; // update solution
return;
}
void JacobiSmoother( VT &sol, const MT &M, const VT &def )
// result in sol_vec; def_vec: correct defect before call, after call destroyed
{
typename VT::Iterator viter(sol);
typename VT::VectorEntry ve;
while(viter(ve))
sol[ve] += def[ve] / M.DiagValue(ve);
return;
}
void JacobiSmoothFG( VT &sol, const MT &M, const VT &def )
// changes only the fine unknowns
// result in sol_vec; def_vec: correct defect before call, after call destroyed
{
typename VT::Iterator viter(sol);
typename VT::VectorEntry ve;
#ifdef USE_UG_DS
while(viter(ve))
if( sol.IsFG(ve) )
sol[ve] = def[ve] / M.DiagValue(ve);
else
sol[ve] = 0; // init other components
#else
while(viter(ve))
if( sol.IsFG(ve) )
sol[ve] += def[ve] / M.DiagValue(ve);
#endif
return;
}
void dampedJacobiSmoother( VT &sol, const MT &M, const VT &def )
// result in sol_vec; def_vec: correct defect before call, after call destroyed
{
static const double omega = 2.0/3.0;
typename VT::Iterator viter(sol);
typename VT::VectorEntry ve;
while(viter(ve))
sol[ve] += omega * def[ve] / M.DiagValue(ve);
return;
}