Clean up preprocess method using the new LinearSolver interface class

Finally we get rid of the explicit solver names that were hard-coded
in the MultigridStep::preprocess method!

dune/solvers/iterationsteps/multigridstep.cc

@@ -5,16 +5,9 @@
 
 #include <dune/solvers/transferoperators/multigridtransfer.hh>
 #include <dune/solvers/solvers/loopsolver.hh>
+#include <dune/solvers/solvers/linearsolver.hh>
 #include <dune/solvers/common/genericvectortools.hh>
 
-#if HAVE_IPOPT
-#include <dune/solvers/solvers/quadraticipopt.hh>
-#endif
-
-#if HAVE_UMFPACK
-#include <dune/solvers/solvers/umfpacksolver.hh>
-#endif
-
 //template<class MatrixType, class VectorType, class BitVectorType>
 //inline
 //const MatrixType* MultigridStep<MatrixType, VectorType, BitVectorType>::
@@ -164,26 +157,12 @@ void MultigridStep<MatrixType, VectorType, BitVectorType>::preprocess()
             dynamic_cast<SmootherType*>(loopBaseSolver->iterationStep_)->ignoreNodes_ = ignoreNodesHierarchy_[0];
 
         }
-        // TODO: The following two #if-clauses do the exactly the same thing: they call setProblem
-        // However, we cannot write the code generically because there is no general abstraction
-        // for solvers that I can call 'setProblem' for.
-#if HAVE_IPOPT
-        else if (typeid(*this->basesolver_) == typeid(QuadraticIPOptSolver<MatrixType,VectorType>)) {
-
-            QuadraticIPOptSolver<MatrixType,VectorType>* ipoptBaseSolver = dynamic_cast<QuadraticIPOptSolver<MatrixType,VectorType>*> (this->basesolver_);
-
-            ipoptBaseSolver->setProblem(*(this->matrixHierarchy_[0]), *this->xHierarchy_[0], this->rhsHierarchy_[0]);
-        }
-#endif
-#if HAVE_UMFPACK
-        else if (typeid(*this->basesolver_) == typeid(Dune::Solvers::UMFPackSolver<MatrixType,VectorType>)) {
+        else if (typeid(*this->basesolver_) == typeid(LinearSolver<MatrixType,VectorType>)) {
 
-            Dune::Solvers::UMFPackSolver<MatrixType,VectorType>* umfpackBaseSolver
-                = dynamic_cast<Dune::Solvers::UMFPackSolver<MatrixType,VectorType>*> (this->basesolver_);
+            LinearSolver<MatrixType,VectorType>* linearBaseSolver = dynamic_cast<LinearSolver<MatrixType,VectorType>*> (this->basesolver_);
 
-            umfpackBaseSolver->setProblem(*(this->matrixHierarchy_[0]), *this->xHierarchy_[0], this->rhsHierarchy_[0]);
+            linearBaseSolver->setProblem(*(this->matrixHierarchy_[0]), *this->xHierarchy_[0], this->rhsHierarchy_[0]);
         }
-#endif
         else {
             DUNE_THROW(SolverError, "You can't use " << typeid(*this->basesolver_).name()
                        << " as a base solver in a MultigridStep!");

[pipping]

Oh, this is such an improvement.

[oliver.sander_at_tu-dresden.de]

To be honest, I've been wanting to do this for the last ten years... seriously.

[lh1887]

This fails for me if I try to use UMFPackSolver as a base solver in the multigridtest.cc :

what(): SolverError [preprocess:/home/mi/lh1887/dune/dune-solvers/dune/solvers/iterationsteps/multigridstep.cc:168]: You can't use N4Dune7Solvers13UMFPackSolverINS_10BCRSMatrixINS_11FieldMatrixIdLi1ELi1EEESaIS4_EEENS_11BlockVectorINS_11FieldVectorIdLi1EEESaIS9_EEEEE as a base solver in a MultigridStep!

Or is there anything wrong with

auto basesolver = Dune::Solvers::UMFPackSolver<Matrix, Vector> (); mgStep.basesolver_ = &basesolver;

I am willing to learn...