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#ifndef ROL_KRYLOVFACTORY_H
#define ROL_KRYLOVFACTORY_H

#include "ROL_Types.hpp"

#include "Teuchos_ParameterList.hpp"
#include "Teuchos_RCP.hpp"

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

namespace ROL {

  template<class Real> // Why is this forward declaration required but not for CG/CR?
  class GMRES;

  template<class Real>
  inline Teuchos::RCP<Krylov<Real> > KrylovFactory( Teuchos::ParameterList &parlist ) {
    EKrylov ekv = StringToEKrylov(
                   parlist.sublist("General").sublist("Krylov").get("Type","Conjugate Gradients"));
    Real absTol  = parlist.sublist("General").sublist("Krylov").get("Absolute Tolerance", 1.e-4);
    Real relTol  = parlist.sublist("General").sublist("Krylov").get("Relative Tolerance", 1.e-2);
    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 Teuchos::rcp( new ConjugateResiduals<Real>(absTol,relTol,maxit,inexact) );
      case KRYLOV_CG: 
        return Teuchos::rcp( new ConjugateGradients<Real>(absTol,relTol,maxit,inexact) );
      case KRYLOV_GMRES:
        return Teuchos::rcp( new GMRES<Real>(parlist) );
      default:        return Teuchos::null;
    }
  }
}

#endif
