/** \brief Function that is called to build the preconditioner
* for the linear operator that is passed in.
*/
LinearOp DiagonallyScaledPreconditionerFactory::buildPreconditionerOperator(LinearOp & lo,PreconditionerState & state) const
{
using Teuchos::RCP;
using Teuchos::rcp_dynamic_cast;
Teko_DEBUG_SCOPE("DiagonallyScaledPreconditionerFactory::buildPreconditionerOperator",10);
TEST_FOR_EXCEPTION(invFactory_==Teuchos::null,std::runtime_error,
"ERROR: Teko::DiagonallyScaledPreconditionerFactory::buildPreconditionerOperator requires that an "
<< "inverse factory has been set. Currently it is null!");
// get diagonal matrix
LinearOp invD = getInvDiagonalOp(lo,Teko::AbsRowSum);
// M = A * invD
ModifiableLinearOp & M = state.getModifiableOp("op_M");
if(scalingType_==COLUMN_SCALING)
M = explicitMultiply(lo,invD,M);
else
M = explicitMultiply(invD,lo,M);
// build inverse operator
ModifiableLinearOp & invM = state.getModifiableOp("op_invM");
if(invM==Teuchos::null)
invM = buildInverse(*invFactory_,M);
else
rebuildInverse(*invFactory_,M,invM);
// return invD * invM
if(scalingType_==COLUMN_SCALING)
return multiply(invD,invM.getConst());
else
return multiply(invM.getConst(),invD);
}
/** \brief Function that is called to build the preconditioner
* for the linear operator that is passed in.
*/
LinearOp IterativePreconditionerFactory::buildPreconditionerOperator(LinearOp & lo,PreconditionerState & state) const
{
TEUCHOS_TEST_FOR_EXCEPTION(precFactory_==Teuchos::null,std::runtime_error,
"ERROR: Teko::IterativePreconditionerFactory::buildPreconditionerOperator requires that a "
<< "preconditioner factory has been set. Currently it is null!");
// build user specified preconditioner
ModifiableLinearOp & invP = state.getModifiableOp("prec");
if(invP==Teuchos::null)
invP = Teko::buildInverse(*precFactory_,lo);
else
Teko::rebuildInverse(*precFactory_,lo,invP);
// // no repititions are required
// if(correctionNum_==0) return invP;
// now build correction operator
LinearOp I = Thyra::identity(lo->range(),"I");
LinearOp AiP = multiply(lo,invP.getConst(),"AiP");
LinearOp correction = add(I,scale(-1.0,AiP)); // I - A * iPA
LinearOp resMap = I; // will map r_n to r_{n+1}
for(unsigned int i=0;i<correctionNum_;i++)
resMap = add(I,multiply(resMap,correction)); // resMap = I + resMap*(I-A*iP)
// iP = (I-A*iP)^{correctionNum}
return multiply(invP.getConst(),resMap);
}
