Teko_IterativePreconditionerFactory.cpp

// @HEADER
// *****************************************************************************
//      Teko: A package for block and physics based preconditioning
//
// Copyright 2010 NTESS and the Teko contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER

// Teko includes
#include "Teko_IterativePreconditionerFactory.hpp"

#include "Teko_PreconditionerInverseFactory.hpp"

namespace Teko {

IterativePreconditionerFactory::IterativePreconditionerFactory()
    : correctionNum_(0), precFactory_(Teuchos::null) {}

IterativePreconditionerFactory::IterativePreconditionerFactory(
    unsigned int correctionNum, const Teuchos::RCP<Teko::InverseFactory>& precFactory)
    : correctionNum_(correctionNum), precFactory_(precFactory) {}

IterativePreconditionerFactory::IterativePreconditionerFactory(
    unsigned int correctionNum, const Teuchos::RCP<Teko::PreconditionerFactory>& precFactory)
    : correctionNum_(correctionNum) {
  precFactory_ = Teuchos::rcp(
      new Teko::PreconditionerInverseFactory(precFactory, precFactory->getRequestHandler()));
}

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);
}

void IterativePreconditionerFactory::initializeFromParameterList(
    const Teuchos::ParameterList& settings) {
  correctionNum_ = 1;
  if (settings.isParameter("Iteration Count"))
    correctionNum_ = settings.get<int>("Iteration Count");

  TEUCHOS_TEST_FOR_EXCEPTION(
      not settings.isParameter("Preconditioner Type"), std::runtime_error,
      "Parameter \"Preconditioner Type\" is required by a Teko::IterativePreconditionerFactory");

  // grab library and preconditioner name
  Teuchos::RCP<const InverseLibrary> il = getInverseLibrary();
  std::string precName                  = settings.get<std::string>("Preconditioner Type");

  // build preconditioner factory
  precFactory_ = il->getInverseFactory(precName);
  TEUCHOS_TEST_FOR_EXCEPTION(
      precFactory_ == Teuchos::null, std::runtime_error,
      "ERROR: \"Preconditioner Type\" = " << precName << " could not be found");
}

Teuchos::RCP<Teuchos::ParameterList> IterativePreconditionerFactory::getRequestedParameters()
    const {
  TEUCHOS_TEST_FOR_EXCEPTION(
      precFactory_ == Teuchos::null, std::runtime_error,
      "ERROR: Teko::IterativePreconditionerFactory::getRequestedParameters requires that a "
          << "preconditioner factory has been set. Currently it is null!");

  return precFactory_->getRequestedParameters();
}

bool IterativePreconditionerFactory::updateRequestedParameters(const Teuchos::ParameterList& pl) {
  TEUCHOS_TEST_FOR_EXCEPTION(
      precFactory_ == Teuchos::null, std::runtime_error,
      "ERROR: Teko::IterativePreconditionerFactory::updateRequestedParameters requires that a "
          << "preconditioner factory has been set. Currently it is null!");

  return precFactory_->updateRequestedParameters(pl);
}

}  // end namespace Teko