ROL_KrylovFactory.hpp

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// @HEADER
// *****************************************************************************
//               Rapid Optimization Library (ROL) Package
//
// Copyright 2014 NTESS and the ROL contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER

#ifndef ROL_KRYLOVFACTORY_H
#define ROL_KRYLOVFACTORY_H

#include "ROL_Ptr.hpp"
#include "ROL_Types.hpp"

#include "ROL_ConjugateGradients.hpp"
#include "ROL_ConjugateResiduals.hpp"
#include "ROL_GMRES.hpp"
#include "ROL_MINRES.hpp"

namespace ROL {
  enum EKrylov{
    KRYLOV_CG = 0,
    KRYLOV_CR,
    KRYLOV_GMRES,
    KRYLOV_MINRES,
    KRYLOV_USERDEFINED,
    KRYLOV_LAST
  };

  inline std::string EKrylovToString(EKrylov type) {
    std::string retString;
    switch(type) {
      case KRYLOV_CG:          retString = "Conjugate Gradients"; break;
      case KRYLOV_CR:          retString = "Conjugate Residuals"; break;
      case KRYLOV_GMRES:       retString = "GMRES";               break;
      case KRYLOV_MINRES:      retString = "MINRES";              break;
      case KRYLOV_USERDEFINED: retString = "User Defined";        break;
      case KRYLOV_LAST:        retString = "Last Type (Dummy)";   break;
      default:                 retString = "INVALID EKrylov";
    }
    return retString;
  }

  inline int isValidKrylov(EKrylov type){
    return( (type == KRYLOV_CG)      ||
            (type == KRYLOV_CR)      ||
            (type == KRYLOV_GMRES)   ||
            (type == KRYLOV_USERDEFINED) );
  }

  inline EKrylov & operator++(EKrylov &type) {
    return type = static_cast<EKrylov>(type+1);
  }

  inline EKrylov operator++(EKrylov &type, int) {
    EKrylov oldval = type;
    ++type;
    return oldval;
  }

  inline EKrylov & operator--(EKrylov &type) {
    return type = static_cast<EKrylov>(type-1);
  }

  inline EKrylov operator--(EKrylov &type, int) {
    EKrylov oldval = type;
    --type;
    return oldval;
  }

  inline EKrylov StringToEKrylov(std::string s) {
    s = removeStringFormat(s);
    for ( EKrylov type = KRYLOV_CG; type < KRYLOV_LAST; type++ ) {
      if ( !s.compare(removeStringFormat(EKrylovToString(type))) ) {
        return type;
      }
    }
    return KRYLOV_CG;
  }

  template<class Real>
  inline Ptr<Krylov<Real>> KrylovFactory( ParameterList &parlist ) {
    Real em4(1e-4), em2(1e-2);
    EKrylov ekv = StringToEKrylov(
                   parlist.sublist("General").sublist("Krylov").get("Type","GMRES"));
    Real absTol  = parlist.sublist("General").sublist("Krylov").get("Absolute Tolerance", em4);
    Real relTol  = parlist.sublist("General").sublist("Krylov").get("Relative Tolerance", em2);
    int maxit    = parlist.sublist("General").sublist("Krylov").get("Iteration Limit", 20);
    bool inexact = parlist.sublist("General").get("Inexact Hessian-Times-A-Vector",false);
    switch(ekv) {
      case KRYLOV_CR: 
        return makePtr<ConjugateResiduals<Real>>(absTol,relTol,maxit,inexact);
      case KRYLOV_CG: 
        return makePtr<ConjugateGradients<Real>>(absTol,relTol,maxit,inexact);
      case KRYLOV_MINRES:
        return makePtr<MINRES<Real>>(absTol,relTol,maxit,inexact);
      case KRYLOV_GMRES:
        return makePtr<GMRES<Real>>(parlist);
      default:
        return nullPtr;
    }
  }

}

#endif