Added missing source file from last commit

dune/istl/test/inverseoperator2prectest.cc

+// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+// vi: set et ts=4 sw=2 sts=2:
+#include "config.h"
+#include<dune/istl/bvector.hh>
+#include<dune/istl/superlu.hh>
+#include<dune/istl/preconditioners.hh>
+#include<dune/istl/solvers.hh>
+#include<dune/istl/operators.hh>
+#include <dune/common/fmatrix.hh>
+#include <dune/common/fvector.hh>
+#include <laplacian.hh>
+
+int main(int argc, char** argv)
+{
+  const int BS=1;
+  int N=100;
+
+  if(argc>1)
+    N = atoi(argv[1]);
+  std::cout<<"testing for N="<<N<<" BS="<<1<<std::endl;
+
+  typedef Dune::FieldMatrix<double,BS,BS> MatrixBlock;
+  typedef Dune::BCRSMatrix<MatrixBlock> BCRSMat;
+  typedef Dune::FieldVector<double,BS> VectorBlock;
+  typedef Dune::BlockVector<VectorBlock> BVector;
+  typedef Dune::MatrixAdapter<BCRSMat,BVector,BVector> Operator;
+
+  BCRSMat mat;
+  Operator fop(mat);
+  BVector b(N*N), x(N*N);
+
+  setupLaplacian(mat,N);
+  b=0;
+  x=100;
+
+  Dune::InverseOperatorResult res, res1;
+  x=1;
+  mat.mv(x, b);
+  x=0;
+  Dune::SeqJac<BCRSMat,BVector,BVector> prec0(mat, 1,1.0);
+  const int category = Dune::SeqJac<BCRSMat,BVector,BVector>::category;
+  Dune::LoopSolver<BVector> solver0(fop, prec0, 1e-3,10,0);
+  Dune::InverseOperator2Preconditioner<Dune::LoopSolver<BVector>,category >
+    prec(solver0);
+  Dune::LoopSolver<BVector> solver(fop, prec, 1e-8,10,2);
+  solver.apply(x,b,res);
+
+  x=1;
+  mat.mv(x, b);
+  x=0;
+  std::cout<<"solver1"<<std::endl;
+  Dune::LoopSolver<BVector> solver1(fop, prec0, 1e-8,100,2);
+  solver1.apply(x,b,res1);
+
+  if(res1.iterations!=res.iterations*10)
+  {
+    std::cerr<<"Convergence rates do not match!"<<std::endl;
+    return 1;
+  }
+  return 0;
+}