diff --git a/tests/solver/Test_wilsonclover_mg.cc b/tests/solver/Test_wilsonclover_mg.cc
new file mode 100644
index 00000000..ebb685cf
--- /dev/null
+++ b/tests/solver/Test_wilsonclover_mg.cc
@@ -0,0 +1,773 @@
+/*************************************************************************************
+
+    Grid physics library, www.github.com/paboyle/Grid 
+
+    Source file: ./tests/solver/Test_wilsonclover_mg.cc
+
+    Copyright (C) 2017
+
+    Author: Daniel Richtmann <daniel.richtmann@ur.de>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+    See the full license in the file "LICENSE" in the top level distribution directory
+    *************************************************************************************/
+/*  END LEGAL */
+
+#include <Grid/Grid.h>
+#include <Grid/algorithms/iterative/PrecGeneralisedConjugateResidual.h>
+
+using namespace std;
+using namespace Grid;
+using namespace Grid::QCD;
+
+template<class Field, int nbasis> class TestVectorAnalyzer {
+public:
+  void operator()(LinearOperatorBase<Field> &Linop, std::vector<Field> const &vectors, int nn = nbasis) {
+
+    auto positiveOnes = 0;
+
+    std::vector<Field> tmp(4, vectors[0]._grid);
+    Gamma              g5(Gamma::Algebra::Gamma5);
+
+    std::cout << GridLogMessage << "Test vector analysis:" << std::endl;
+
+    for(auto i = 0; i < nn; ++i) {
+
+      Linop.Op(vectors[i], tmp[3]);
+
+      tmp[0] = g5 * tmp[3];
+
+      auto lambda = innerProduct(vectors[i], tmp[0]) / innerProduct(vectors[i], vectors[i]);
+
+      tmp[1] = tmp[0] - lambda * vectors[i];
+
+      auto mu = ::sqrt(norm2(tmp[1]) / norm2(vectors[i]));
+
+      auto nrm = ::sqrt(norm2(vectors[i]));
+
+      if(real(lambda) > 0)
+        positiveOnes++;
+
+      std::cout << GridLogMessage << std::scientific << std::setprecision(2) << std::setw(2) << std::showpos << "vector " << i << ": "
+                << "singular value: " << lambda << ", singular vector precision: " << mu << ", norm: " << nrm << std::endl;
+    }
+    std::cout << GridLogMessage << std::scientific << std::setprecision(2) << std::setw(2) << std::showpos << positiveOnes << " out of " << nn
+              << " vectors were positive" << std::endl;
+  }
+};
+
+class myclass : Serializable {
+public:
+  // clang-format off
+  GRID_SERIALIZABLE_CLASS_MEMBERS(myclass,
+                                  int, domaindecompose,
+                                  int, domainsize,
+                                  int, coarsegrids,
+                                  int, order,
+                                  int, Ls,
+                                  double, mq,
+                                  double, lo,
+                                  double, hi,
+                                  int, steps);
+  // clang-format on
+  myclass(){};
+};
+myclass params;
+
+template<int nbasis> struct CoarseGrids {
+public:
+  std::vector<std::vector<int>> LattSizes;
+  std::vector<std::vector<int>> Seeds;
+  std::vector<GridCartesian *>  Grids;
+  std::vector<GridParallelRNG>  PRNGs;
+
+  CoarseGrids(std::vector<std::vector<int>> const &blockSizes, int coarsegrids) {
+
+    assert(blockSizes.size() == coarsegrids);
+
+    std::cout << GridLogMessage << "Constructing " << coarsegrids << " CoarseGrids" << std::endl;
+
+    for(int cl = 0; cl < coarsegrids; ++cl) { // may be a bit ugly and slow but not perf critical
+      // need to differentiate between first and other coarse levels in size calculation
+      LattSizes.push_back({cl == 0 ? GridDefaultLatt() : LattSizes[cl - 1]});
+      Seeds.push_back(std::vector<int>(LattSizes[cl].size()));
+
+      for(int d = 0; d < LattSizes[cl].size(); ++d) {
+        LattSizes[cl][d] = LattSizes[cl][d] / blockSizes[cl][d];
+        Seeds[cl][d]     = (cl + 1) * LattSizes[cl].size() + d + 1;
+        // calculation unimportant, just to get. e.g., {5, 6, 7, 8} for first coarse level and so on
+      }
+
+      Grids.push_back(SpaceTimeGrid::makeFourDimGrid(LattSizes[cl], GridDefaultSimd(Nd, vComplex::Nsimd()), GridDefaultMpi()));
+      PRNGs.push_back(GridParallelRNG(Grids[cl]));
+
+      PRNGs[cl].SeedFixedIntegers(Seeds[cl]);
+
+      std::cout << GridLogMessage << "cl = " << cl << ": LattSize = " << LattSizes[cl] << std::endl;
+      std::cout << GridLogMessage << "cl = " << cl << ":    Seeds = " << Seeds[cl] << std::endl;
+    }
+  }
+};
+
+template<class Field> void testLinearOperator(LinearOperatorBase<Field> &LinOp, GridBase *Grid, std::string const &name = "") {
+
+  std::vector<int> seeds({1, 2, 3, 4});
+  GridParallelRNG  RNG(Grid);
+  RNG.SeedFixedIntegers(seeds);
+
+  {
+    std::cout << GridLogMessage << "Testing that Mdiag + Σ_μ Mdir_μ == M for operator " << name << ":" << std::endl;
+
+    // clang-format off
+    Field src(Grid);    random(RNG, src);
+    Field ref(Grid);    ref    = zero;
+    Field result(Grid); result = zero;
+    Field diag(Grid);   diag   = zero;
+    Field sumDir(Grid); sumDir = zero;
+    Field tmp(Grid);
+    Field err(Grid);
+    // clang-format on
+
+    LinOp.Op(src, ref);
+    std::cout << GridLogMessage << " norm2(M * src)            = " << norm2(ref) << std::endl;
+
+    LinOp.OpDiag(src, diag);
+    std::cout << GridLogMessage << " norm2(Mdiag * src)        = " << norm2(diag) << std::endl;
+
+    for(int dir = 0; dir < 4; dir++) {
+      for(auto disp : {+1, -1}) {
+        LinOp.OpDir(src, tmp, dir, disp);
+        std::cout << GridLogMessage << " norm2(Mdir_{" << dir << "," << disp << "} * src) = " << norm2(tmp) << std::endl;
+        sumDir = sumDir + tmp;
+      }
+    }
+    std::cout << GridLogMessage << " norm2(Σ_μ Mdir_μ * src)   = " << norm2(sumDir) << std::endl;
+
+    result = diag + sumDir;
+    err    = ref - result;
+
+    std::cout << GridLogMessage << " Absolute deviation        = " << norm2(err) << std::endl;
+    std::cout << GridLogMessage << " Relative deviation        = " << norm2(err) / norm2(ref) << std::endl;
+  }
+
+  {
+    std::cout << GridLogMessage << "Testing hermiticity stochastically for operator " << name << ":" << std::endl;
+
+    // clang-format off
+    Field phi(Grid); random(RNG, phi);
+    Field chi(Grid); random(RNG, chi);
+    Field MPhi(Grid);
+    Field MdagChi(Grid);
+    // clang-format on
+
+    LinOp.Op(phi, MPhi);
+    LinOp.AdjOp(chi, MdagChi);
+
+    ComplexD chiMPhi    = innerProduct(chi, MPhi);
+    ComplexD phiMdagChi = innerProduct(phi, MdagChi);
+
+    ComplexD phiMPhi    = innerProduct(phi, MPhi);
+    ComplexD chiMdagChi = innerProduct(chi, MdagChi);
+
+    std::cout << GridLogMessage << " chiMPhi = " << chiMPhi << " phiMdagChi = " << phiMdagChi << " difference = " << chiMPhi - conjugate(phiMdagChi)
+              << std::endl;
+
+    std::cout << GridLogMessage << " phiMPhi = " << phiMPhi << " chiMdagChi = " << chiMdagChi << " <- should be real if hermitian" << std::endl;
+  }
+
+  {
+    std::cout << GridLogMessage << "Testing linearity for operator " << name << ":" << std::endl;
+
+    // clang-format off
+    Field phi(Grid); random(RNG, phi);
+    Field chi(Grid); random(RNG, chi);
+    Field phiPlusChi(Grid);
+    Field MPhi(Grid);
+    Field MChi(Grid);
+    Field MPhiPlusChi(Grid);
+    Field linearityError(Grid);
+    // clang-format on
+
+    LinOp.Op(phi, MPhi);
+    LinOp.Op(chi, MChi);
+
+    phiPlusChi = phi + chi;
+
+    LinOp.Op(phiPlusChi, MPhiPlusChi);
+
+    linearityError = MPhiPlusChi - MPhi;
+    linearityError = linearityError - MChi;
+
+    std::cout << GridLogMessage << " norm2(linearityError) = " << norm2(linearityError) << std::endl;
+  }
+}
+
+// template < class Fobj, class CComplex, int coarseSpins, int nbasis, class Matrix >
+// class MultiGridPreconditioner : public LinearFunction< Lattice< Fobj > > {
+template<class Fobj, class CComplex, int nbasis, class Matrix> class MultiGridPreconditioner : public LinearFunction<Lattice<Fobj>> {
+public:
+  typedef Aggregation<Fobj, CComplex, nbasis>     Aggregates;
+  typedef CoarsenedMatrix<Fobj, CComplex, nbasis> CoarseOperator;
+
+  typedef typename Aggregation<Fobj, CComplex, nbasis>::siteVector   siteVector;
+  typedef typename Aggregation<Fobj, CComplex, nbasis>::CoarseScalar CoarseScalar;
+  typedef typename Aggregation<Fobj, CComplex, nbasis>::CoarseVector CoarseVector;
+  typedef typename Aggregation<Fobj, CComplex, nbasis>::CoarseMatrix CoarseMatrix;
+  typedef typename Aggregation<Fobj, CComplex, nbasis>::FineField    FineField;
+  typedef LinearOperatorBase<FineField>                              FineOperator;
+
+  Aggregates &    _Aggregates;
+  CoarseOperator &_CoarseOperator;
+  Matrix &        _FineMatrix;
+  FineOperator &  _FineOperator;
+  Matrix &        _SmootherMatrix;
+  FineOperator &  _SmootherOperator;
+
+  // Constructor
+  MultiGridPreconditioner(Aggregates &    Agg,
+                          CoarseOperator &Coarse,
+                          FineOperator &  Fine,
+                          Matrix &        FineMatrix,
+                          FineOperator &  Smooth,
+                          Matrix &        SmootherMatrix)
+    : _Aggregates(Agg)
+    , _CoarseOperator(Coarse)
+    , _FineOperator(Fine)
+    , _FineMatrix(FineMatrix)
+    , _SmootherOperator(Smooth)
+    , _SmootherMatrix(SmootherMatrix) {}
+
+  void operator()(const FineField &in, FineField &out) {
+
+    CoarseVector coarseSrc(_CoarseOperator.Grid());
+    CoarseVector coarseTmp(_CoarseOperator.Grid());
+    CoarseVector coarseSol(_CoarseOperator.Grid());
+    coarseSol = zero;
+
+    GeneralisedMinimalResidual<CoarseVector> coarseGMRES(5.0e-2, 100, 25, false);
+    GeneralisedMinimalResidual<FineField>    fineGMRES(5.0e-2, 100, 25, false);
+
+    HermitianLinearOperator<CoarseOperator, CoarseVector> coarseHermOp(_CoarseOperator);
+    MdagMLinearOperator<CoarseOperator, CoarseVector>     coarseMdagMOp(_CoarseOperator);
+    MdagMLinearOperator<Matrix, FineField>                fineMdagMOp(_SmootherMatrix);
+
+    FineField fineTmp1(in._grid);
+    FineField fineTmp2(in._grid);
+
+    RealD Ni = norm2(in);
+
+    // no pre smoothing for now
+    auto  preSmootherNorm     = 0;
+    auto  preSmootherResidual = 0;
+    RealD r;
+
+    // Project to coarse grid, solve, project back to fine grid
+    _Aggregates.ProjectToSubspace(coarseSrc, in);
+    coarseGMRES(coarseMdagMOp, coarseSrc, coarseSol);
+    _Aggregates.PromoteFromSubspace(coarseSol, out);
+
+    // Recompute error
+    _FineOperator.Op(out, fineTmp1);
+    fineTmp1            = in - fineTmp1;
+    r                   = norm2(fineTmp1);
+    auto coarseResidual = std::sqrt(r / Ni);
+
+    // Apply smoother, use GMRES for the moment
+    fineGMRES(fineMdagMOp, in, out);
+
+    // Recompute error
+    _FineOperator.Op(out, fineTmp1);
+    fineTmp1                  = in - fineTmp1;
+    r                         = norm2(fineTmp1);
+    auto postSmootherResidual = std::sqrt(r / Ni);
+
+    std::cout << GridLogIterative << "Input norm = " << Ni << " Pre-Smoother norm " << preSmootherNorm
+              << " Pre-Smoother residual = " << preSmootherResidual << " Coarse residual = " << coarseResidual
+              << " Post-Smoother residual = " << postSmootherResidual << std::endl;
+  }
+
+  void runChecks(CoarseGrids<nbasis> &cGrids, int whichCoarseGrid) {
+
+    /////////////////////////////////////////////
+    // Some stuff we need for the checks below //
+    /////////////////////////////////////////////
+    auto tolerance = 1e-13; // TODO: this obviously depends on the precision we use, current value is for double
+
+    std::vector<CoarseVector> cTmps(4, _CoarseOperator.Grid());
+    std::vector<FineField>    fTmps(2, _Aggregates.subspace[0]._grid); // atm only for one coarser grid
+
+    // need to construct an operator, since _CoarseOperator is not a LinearOperator but only a matrix (the name is a bit misleading)
+    MdagMLinearOperator<CoarseOperator, CoarseVector> MdagMOp(_CoarseOperator);
+
+    std::cout << GridLogMessage << "**************************************************" << std::endl;
+    std::cout << GridLogMessage << "MG correctness check: 0 == (1 - P R) v" << std::endl;
+    std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    for(auto i = 0; i < _Aggregates.subspace.size(); ++i) {
+      _Aggregates.ProjectToSubspace(cTmps[0], _Aggregates.subspace[i]); //   R v_i
+      _Aggregates.PromoteFromSubspace(cTmps[0], fTmps[0]);              // P R v_i
+
+      fTmps[1]       = _Aggregates.subspace[i] - fTmps[0]; // v_i - P R v_i
+      auto deviation = std::sqrt(norm2(fTmps[1]) / norm2(_Aggregates.subspace[i]));
+
+      std::cout << GridLogMessage << "Vector " << i << ": norm2(v_i) = " << norm2(_Aggregates.subspace[i]) << " | norm2(R v_i) = " << norm2(cTmps[0])
+                << " | norm2(P R v_i) = " << norm2(fTmps[0]) << " | relative deviation = " << deviation;
+
+      if(deviation > tolerance) {
+        std::cout << " > " << tolerance << " -> check failed" << std::endl;
+        // abort();
+      } else {
+        std::cout << " < " << tolerance << " -> check passed" << std::endl;
+      }
+    }
+
+    std::cout << GridLogMessage << "**************************************************" << std::endl;
+    std::cout << GridLogMessage << "MG correctness check: 0 == (1 - R P) v_c" << std::endl;
+    std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    random(cGrids.PRNGs[whichCoarseGrid], cTmps[0]);
+
+    _Aggregates.PromoteFromSubspace(cTmps[0], fTmps[0]); //   P v_c
+    _Aggregates.ProjectToSubspace(cTmps[1], fTmps[0]);   // R P v_c
+
+    cTmps[2]       = cTmps[0] - cTmps[1]; // v_c - R P v_c
+    auto deviation = std::sqrt(norm2(cTmps[2]) / norm2(cTmps[0]));
+
+    std::cout << GridLogMessage << "norm2(v_c) = " << norm2(cTmps[0]) << " | norm2(R P v_c) = " << norm2(cTmps[1])
+              << " | norm2(P v_c) = " << norm2(fTmps[0]) << " | relative deviation = " << deviation;
+
+    if(deviation > tolerance) {
+      std::cout << " > " << tolerance << " -> check failed" << std::endl;
+      // abort();
+    } else {
+      std::cout << " < " << tolerance << " -> check passed" << std::endl;
+    }
+
+    std::cout << GridLogMessage << "**************************************************" << std::endl;
+    std::cout << GridLogMessage << "MG correctness check: 0 == (R D P - D_c) v_c" << std::endl;
+    std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    random(cGrids.PRNGs[whichCoarseGrid], cTmps[0]);
+
+    _Aggregates.PromoteFromSubspace(cTmps[0], fTmps[0]); //     P v_c
+    _FineOperator.Op(fTmps[0], fTmps[1]);                //   D P v_c
+    _Aggregates.ProjectToSubspace(cTmps[1], fTmps[1]);   // R D P v_c
+
+    MdagMOp.Op(cTmps[0], cTmps[2]); // D_c v_c
+
+    cTmps[3]  = cTmps[1] - cTmps[2]; // R D P v_c - D_c v_c
+    deviation = std::sqrt(norm2(cTmps[3]) / norm2(cTmps[1]));
+
+    std::cout << GridLogMessage << "norm2(R D P v_c) = " << norm2(cTmps[1]) << " | norm2(D_c v_c) = " << norm2(cTmps[2])
+              << " | relative deviation = " << deviation;
+
+    if(deviation > tolerance) {
+      std::cout << " > " << tolerance << " -> check failed" << std::endl;
+      // abort();
+    } else {
+      std::cout << " < " << tolerance << " -> check passed" << std::endl;
+    }
+
+    std::cout << GridLogMessage << "**************************************************" << std::endl;
+    std::cout << GridLogMessage << "MG correctness check: 0 == |(Im(v_c^dag D_c^dag D_c v_c)|" << std::endl;
+    std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    random(cGrids.PRNGs[whichCoarseGrid], cTmps[0]);
+
+    MdagMOp.Op(cTmps[0], cTmps[1]);    //         D_c v_c
+    MdagMOp.AdjOp(cTmps[1], cTmps[2]); // D_c^dag D_c v_c
+
+    auto dot  = innerProduct(cTmps[0], cTmps[2]); //v_c^dag D_c^dag D_c v_c
+    deviation = abs(imag(dot)) / abs(real(dot));
+
+    std::cout << GridLogMessage << "Re(v_c^dag D_c^dag D_c v_c) = " << real(dot) << " | Im(v_c^dag D_c^dag D_c v_c) = " << imag(dot)
+              << " | relative deviation = " << deviation;
+
+    if(deviation > tolerance) {
+      std::cout << " > " << tolerance << " -> check failed" << std::endl;
+      // abort();
+    } else {
+      std::cout << " < " << tolerance << " -> check passed" << std::endl;
+    }
+  }
+};
+
+int main(int argc, char **argv) {
+
+  Grid_init(&argc, &argv);
+
+  params.domainsize      = 1;
+  params.coarsegrids     = 1;
+  params.domaindecompose = 0;
+  params.order           = 30;
+  params.Ls              = 1;
+  params.mq              = -0.5;
+  params.lo              = 0.5;
+  params.hi              = 70.0;
+  params.steps           = 1;
+
+  typedef typename WilsonCloverFermionR::FermionField FermionField;
+  typename WilsonCloverFermionR::ImplParams           wcImplparams;
+  WilsonAnisotropyCoefficients                        wilsonAnisCoeff;
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Params: " << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  std::cout << params << std::endl;
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Set up some fine level stuff: " << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  GridCartesian *        FGrid   = SpaceTimeGrid::makeFourDimGrid(GridDefaultLatt(), GridDefaultSimd(Nd, vComplex::Nsimd()), GridDefaultMpi());
+  GridRedBlackCartesian *FrbGrid = SpaceTimeGrid::makeFourDimRedBlackGrid(FGrid);
+
+  std::vector<int> fSeeds({1, 2, 3, 4});
+  GridParallelRNG  fPRNG(FGrid);
+  fPRNG.SeedFixedIntegers(fSeeds);
+
+  Gamma g5(Gamma::Algebra::Gamma5);
+
+  // clang-format off
+  FermionField        src(FGrid); gaussian(fPRNG, src);
+  FermionField     result(FGrid); result = zero;
+  LatticeGaugeField     Umu(FGrid); SU3::HotConfiguration(fPRNG, Umu);
+  // clang-format on
+
+  RealD mass = params.mq;
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Set up some coarser levels stuff: " << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  const int nbasis = 20; // fix the number of test vector to the same
+                         // number on every level for now
+
+  //////////////////////////////////////////
+  // toggle to run two/three level method
+  //////////////////////////////////////////
+
+  // two-level algorithm
+  std::vector<std::vector<int>> blockSizes({{2, 2, 2, 2}});
+  CoarseGrids<nbasis>           coarseGrids(blockSizes, 1);
+
+  // // three-level algorithm
+  // std::vector<std::vector<int>> blockSizes({{2, 2, 2, 2}, {2, 2, 1, 1}});
+  // CoarseGrids<nbasis>           coarseGrids(blockSizes, 2);
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Some typedefs" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  // typedefs for transition from fine to first coarsened grid
+  typedef vSpinColourVector                                                                       FineSiteVector;
+  typedef vTComplex                                                                               CoarseSiteScalar;
+  typedef Aggregation<FineSiteVector, CoarseSiteScalar, nbasis>                                   Subspace;
+  typedef CoarsenedMatrix<FineSiteVector, CoarseSiteScalar, nbasis>                               CoarseOperator;
+  typedef CoarseOperator::CoarseVector                                                            CoarseVector;
+  typedef CoarseOperator::siteVector                                                              CoarseSiteVector;
+  typedef TestVectorAnalyzer<FermionField, nbasis>                                                FineTVA;
+  typedef MultiGridPreconditioner<FineSiteVector, CoarseSiteScalar, nbasis, WilsonCloverFermionR> FineMGPreconditioner;
+  typedef TrivialPrecon<FermionField>                                                             FineTrivialPreconditioner;
+
+  // typedefs for transition from a coarse to the next coarser grid (some defs remain the same)
+  typedef Aggregation<CoarseSiteVector, CoarseSiteScalar, nbasis>                             SubSubSpace;
+  typedef CoarsenedMatrix<CoarseSiteVector, CoarseSiteScalar, nbasis>                         CoarseCoarseOperator;
+  typedef CoarseCoarseOperator::CoarseVector                                                  CoarseCoarseVector;
+  typedef CoarseCoarseOperator::siteVector                                                    CoarseCoarseSiteVector;
+  typedef TestVectorAnalyzer<CoarseVector, nbasis>                                            CoarseTVA;
+  typedef MultiGridPreconditioner<CoarseSiteVector, CoarseSiteScalar, nbasis, CoarseOperator> CoarseMGPreconditioner;
+  typedef TrivialPrecon<CoarseVector>                                                         CoarseTrivialPreconditioner;
+
+  static_assert(std::is_same<CoarseVector, CoarseCoarseVector>::value, "CoarseVector and CoarseCoarseVector must be of the same type");
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Building the wilson clover operator on the fine grid" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  RealD                csw_r = 1.0;
+  RealD                csw_t = 1.0;
+  WilsonCloverFermionR Dwc(Umu, *FGrid, *FrbGrid, mass, csw_r, csw_t, wilsonAnisCoeff, wcImplparams);
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Setting up linear operators" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  MdagMLinearOperator<WilsonCloverFermionR, FermionField> FineMdagMOp(Dwc);
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Calling Aggregation class to build subspaces" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  Subspace FineAggregates(coarseGrids.Grids[0], FGrid, 0);
+
+  assert((nbasis & 0x1) == 0);
+  int nb = nbasis / 2;
+  std::cout << GridLogMessage << " nbasis/2 = " << nb << std::endl;
+
+  FineAggregates.CreateSubspace(fPRNG, FineMdagMOp /*, nb */); // Don't specify nb to see the orthogonalization check
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Test vector analysis after initial creation of subspace" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  FineTVA fineTVA;
+  fineTVA(FineMdagMOp, FineAggregates.subspace);
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Projecting subspace to definite chirality" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  for(int n = 0; n < nb; n++) {
+    FineAggregates.subspace[n + nb] = g5 * FineAggregates.subspace[n];
+  }
+
+  auto coarseSites = 1;
+  for(auto const &elem : coarseGrids.LattSizes[0]) coarseSites *= elem;
+
+  std::cout << GridLogMessage << "Norms of MG test vectors after chiral projection (coarse sites = " << coarseSites << ")" << std::endl;
+  for(int n = 0; n < nbasis; n++) {
+    std::cout << GridLogMessage << "vec[" << n << "] = " << norm2(FineAggregates.subspace[n]) << std::endl;
+  }
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Building coarse representation of Dirac operator" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  CoarseOperator Dc(*coarseGrids.Grids[0]);
+
+  Dc.CoarsenOperator(FGrid, FineMdagMOp, FineAggregates);
+
+  MdagMLinearOperator<CoarseOperator, CoarseVector> CoarseMdagMOp(Dc);
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Test vector analysis after construction of coarse Dirac operator" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  fineTVA(FineMdagMOp, FineAggregates.subspace);
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Testing the linear operators" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  // clang-format off
+  testLinearOperator(FineMdagMOp,   FGrid,                "FineMdagMOp");   std::cout << GridLogMessage << std::endl;
+  testLinearOperator(CoarseMdagMOp, coarseGrids.Grids[0], "CoarseMdagMOp"); std::cout << GridLogMessage << std::endl;
+  // clang-format on
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Building coarse vectors" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  CoarseVector coarseSource(coarseGrids.Grids[0]);
+  CoarseVector coarseResult(coarseGrids.Grids[0]);
+  gaussian(coarseGrids.PRNGs[0], coarseSource);
+  coarseResult = zero;
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Building some coarse space solvers" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  std::vector<std::unique_ptr<OperatorFunction<CoarseVector>>> dummyCoarseSolvers;
+  dummyCoarseSolvers.emplace_back(new GeneralisedMinimalResidual<CoarseVector>(5.0e-2, 100, 8, false));
+  dummyCoarseSolvers.emplace_back(new MinimalResidual<CoarseVector>(5.0e-2, 100, 0.8, false));
+  dummyCoarseSolvers.emplace_back(new ConjugateGradient<CoarseVector>(5.0e-2, 100, false));
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Testing some coarse space solvers" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  std::cout << GridLogMessage << "checking norm of coarse src " << norm2(coarseSource) << std::endl;
+
+  for(auto const &solver : dummyCoarseSolvers) {
+    coarseResult = zero;
+    (*solver)(CoarseMdagMOp, coarseSource, coarseResult);
+  }
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Building a multigrid preconditioner" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  FineMGPreconditioner      FineMGPrecon(FineAggregates, Dc, FineMdagMOp, Dwc, FineMdagMOp, Dwc);
+  FineTrivialPreconditioner FineSimplePrecon;
+
+  FineMGPrecon.runChecks(coarseGrids, 0);
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Building krylov subspace solvers w/ & w/o MG Preconditioner" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  std::vector<std::unique_ptr<OperatorFunction<FermionField>>> solvers;
+  solvers.emplace_back(new FlexibleGeneralisedMinimalResidual<FermionField>(1.0e-12, 4000000, FineSimplePrecon, 25, false));
+  solvers.emplace_back(new FlexibleGeneralisedMinimalResidual<FermionField>(1.0e-12, 100, FineMGPrecon, 25, false));
+  solvers.emplace_back(new PrecGeneralisedConjugateResidual<FermionField>(1.0e-12, 4000000, FineSimplePrecon, 25, 25));
+
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+  std::cout << GridLogMessage << "Testing the (un)?preconditioned solvers" << std::endl;
+  std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+  for(auto const &solver : solvers) {
+    std::cout << GridLogMessage << "checking norm of fine src " << norm2(src) << std::endl;
+    result = zero;
+    (*solver)(FineMdagMOp, src, result);
+    std::cout << std::endl;
+  }
+
+#if 0
+  if(coarseGrids.LattSizes.size() == 2) {
+
+    std::cout << GridLogMessage << "**************************************************" << std::endl;
+    std::cout << GridLogMessage << "Some testing for construction of a second coarse level" << std::endl;
+    std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+    // std::cout << GridLogMessage << "Calling Aggregation class to build subspaces" << std::endl;
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    SubSubSpace CoarseAggregates(coarseGrids.Grids[1], coarseGrids.Grids[0], 0);
+    CoarseAggregates.CreateSubspace(coarseGrids.PRNGs[0], CoarseMdagMOp);
+
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+    // std::cout << GridLogMessage << "Test vector analysis after initial creation of subspace" << std::endl;
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    // // this doesn't work because this function applies g5 to a vector, which
+    // // doesn't work for coarse vectors atm -> FIXME
+    // CoarseTVA coarseTVA;
+    // coarseTVA(CoarseMdagMOp, CoarseAggregates.subspace);
+
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+    // std::cout << GridLogMessage << "Projecting subspace to definite chirality" << std::endl;
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    // // cannot apply g5 to coarse vectors atm -> FIXME
+    // for(int n=0;n<nb;n++){
+    //   CoarseAggregates.subspace[n+nb] = g5 * CoarseAggregates.subspace[n];
+    //   std::cout<<GridLogMessage<<n<<" subspace "<<norm2(CoarseAggregates.subspace[n+nb])<<" "<<norm2(CoarseAggregates.subspace[n]) <<std::endl;
+    // }
+
+    auto coarseCoarseSites = 1;
+    for(auto const &elem : coarseGrids.LattSizes[1]) coarseCoarseSites *= elem;
+
+    std::cout << GridLogMessage << "Norms of MG test vectors after chiral projection (coarse coarse sites = " << coarseCoarseSites << ")"
+              << std::endl;
+    for(int n = 0; n < nbasis; n++) {
+      std::cout << GridLogMessage << "vec[" << n << "] = " << norm2(CoarseAggregates.subspace[n]) << std::endl;
+    }
+
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+    // std::cout << GridLogMessage << "Building coarse coarse representation of Dirac operator" << std::endl;
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    CoarseCoarseOperator Dcc(*coarseGrids.Grids[1]);
+
+    Dcc.CoarsenOperator(coarseGrids.Grids[0], CoarseMdagMOp, CoarseAggregates);
+
+    MdagMLinearOperator<CoarseCoarseOperator, CoarseCoarseVector> CoarseCoarseMdagMOp(Dcc);
+
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+    // std::cout << GridLogMessage << "Test vector analysis after construction of coarse Dirac operator" << std::endl;
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    // // this doesn't work because this function applies g5 to a vector, which
+    // // doesn't work for coarse vectors atm -> FIXME
+    // coarseTVA(CoarseMdagMOp, CoarseAggregates.subspace);
+
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+    // std::cout << GridLogMessage << "Testing the linear operators" << std::endl;
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    // clang-format off
+    testLinearOperator(CoarseMdagMOp,       coarseGrids.Grids[0], "CoarseMdagMOp");
+    testLinearOperator(CoarseCoarseMdagMOp, coarseGrids.Grids[1], "CoarseCoarseMdagMOp");
+    // clang-format on
+
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+    // std::cout << GridLogMessage << "Building coarse coarse vectors" << std::endl;
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    CoarseCoarseVector coarseCoarseSource(coarseGrids.Grids[1]);
+    CoarseCoarseVector coarseCoarseResult(coarseGrids.Grids[1]);
+    gaussian(coarseGrids.PRNGs[1], coarseCoarseSource);
+    coarseCoarseResult = zero;
+
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+    // std::cout << GridLogMessage << "Building some coarse space solvers" << std::endl;
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    std::vector<std::unique_ptr<OperatorFunction<CoarseCoarseVector>>> dummyCoarseCoarseSolvers;
+    dummyCoarseCoarseSolvers.emplace_back(new GeneralisedMinimalResidual<CoarseCoarseVector>(5.0e-2, 100, 8, false));
+    dummyCoarseCoarseSolvers.emplace_back(new MinimalResidual<CoarseCoarseVector>(5.0e-2, 100, false));
+    dummyCoarseCoarseSolvers.emplace_back(new ConjugateGradient<CoarseCoarseVector>(5.0e-2, 100, false));
+
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+    // std::cout << GridLogMessage << "Testing some coarse coarse space solvers" << std::endl;
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    std::cout << GridLogMessage << "checking norm of coarse coarse src " << norm2(coarseCoarseSource) << std::endl;
+
+    for(auto const &solver : dummyCoarseCoarseSolvers) {
+      coarseCoarseResult = zero;
+      (*solver)(CoarseCoarseMdagMOp, coarseCoarseSource, coarseCoarseResult);
+    }
+
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+    // std::cout << GridLogMessage << "Building a multigrid preconditioner" << std::endl;
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    CoarseMGPreconditioner      CoarseMGPrecon(CoarseAggregates, Dcc, CoarseMdagMOp, Dc, CoarseMdagMOp, Dc);
+    CoarseTrivialPreconditioner CoarseSimplePrecon;
+
+    CoarseMGPrecon.runChecks(coarseGrids, 1);
+
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+    // std::cout << GridLogMessage << "Building krylov subspace solvers w/ & w/o MG Preconditioner" << std::endl;
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    std::vector<std::unique_ptr<OperatorFunction<CoarseVector>>> solvers;
+    solvers.emplace_back(new FlexibleGeneralisedMinimalResidual<CoarseVector>(1.0e-12, 4000000, CoarseSimplePrecon, 25, false));
+    solvers.emplace_back(new FlexibleGeneralisedMinimalResidual<CoarseVector>(1.0e-12, 100, CoarseMGPrecon, 25, false));
+    solvers.emplace_back(new PrecGeneralisedConjugateResidual<CoarseVector>(1.0e-12, 4000000, CoarseSimplePrecon, 25, 25));
+
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+    // std::cout << GridLogMessage << "Testing the (un)?preconditioned solvers" << std::endl;
+    // std::cout << GridLogMessage << "**************************************************" << std::endl;
+
+    for(auto const &solver : solvers) {
+      std::cout << GridLogMessage << "checking norm of fine src " << norm2(coarseSource) << std::endl;
+      coarseResult = zero;
+      (*solver)(CoarseMdagMOp, coarseSource, coarseResult);
+      std::cout << std::endl;
+    }
+
+  }
+#endif
+
+  Grid_finalize();
+}
+
+// Ideas compiled during discussions with the others during lunchtime:
+//
+// • set the gauge fields to 0
+//   -> the hopping term is zero -> M is the same as Mdiag
+// • set the mass to minus 4
+//   -> the self coupling term is zero -> M is the same as Σ_u Mdir_μ
+//
+// In both cases it's probably a good idea to set the source fermion to 1
+
+// I just put this here to have it out of the way in main
+// This code is intended to be put after the creation of the first MG Preconditioner object for the fine grid.