CG test written and passes i.e. converges with small true residual

in RedBlack MpcDagMpc, Unprec MdagM and Schur red black solver for
each of.

DomainWallFermion
MobiusFermion
MobiusZolotarevFermion
ScaledShamirFermion
ScaledShamirZolotarevFermion

tests/Test_nersc_io.cc

@@ -0,0 +1,93 @@
+#include <Grid.h>
+#include <parallelIO/GridNerscIO.h>
+
+using namespace std;
+using namespace Grid;
+using namespace Grid::QCD;
+
+
+int main (int argc, char ** argv)
+{
+  Grid_init(&argc,&argv);
+
+
+  std::vector<int> simd_layout = GridDefaultSimd(4,vComplexF::Nsimd());
+  std::vector<int> mpi_layout  = GridDefaultMpi();
+  std::vector<int> latt_size   = GridDefaultLatt();
+  std::vector<int> clatt_size  ({4,4,4,8});
+  int orthodir=3;
+  int orthosz =latt_size[orthodir];
+    
+  GridCartesian     Fine(latt_size,simd_layout,mpi_layout);
+  GridCartesian     Coarse(clatt_size,simd_layout,mpi_layout);
+
+  LatticeGaugeField Umu(&Fine);
+
+  std::vector<LatticeColourMatrix> U(4,&Fine);
+  
+  NerscField header;
+  
+  std::string file("./ckpoint_lat.4000");
+  readNerscConfiguration(Umu,header,file);
+
+  for(int mu=0;mu<Nd;mu++){
+    U[mu] = peekIndex<3>(Umu,mu);
+  }
+
+  // Painful ; fix syntactical niceness
+  LatticeComplex LinkTrace(&Fine);
+  LinkTrace=zero;
+  for(int mu=0;mu<Nd;mu++){
+    LinkTrace = LinkTrace + trace(U[mu]);
+  }
+
+  // (1+2+3)=6 = N(N-1)/2 terms
+  LatticeComplex Plaq(&Fine);
+  LatticeComplex cPlaq(&Coarse);
+
+  Plaq = zero;
+#if 1
+  for(int mu=1;mu<Nd;mu++){
+    for(int nu=0;nu<mu;nu++){
+      Plaq = Plaq + trace(U[mu]*Cshift(U[nu],mu,1)*adj(Cshift(U[mu],nu,1))*adj(U[nu]));
+    }
+  }
+#endif
+  double vol = Fine.gSites();
+  Complex PlaqScale(1.0/vol/6.0/3.0);
+  std::cout <<"PlaqScale" << PlaqScale<<std::endl;
+
+  std::vector<TComplex> Plaq_T(orthosz);
+  sliceSum(Plaq,Plaq_T,Nd-1);
+  int Nt = Plaq_T.size();
+
+  TComplex Plaq_T_sum; 
+  Plaq_T_sum=zero;
+  for(int t=0;t<Nt;t++){
+    Plaq_T_sum = Plaq_T_sum+Plaq_T[t];
+    Complex Pt=TensorRemove(Plaq_T[t]);
+    std::cout << "sliced ["<<t<<"]" <<Pt*PlaqScale*Real(Nt)<<std::endl;
+  }
+
+  {
+    Complex Pt = TensorRemove(Plaq_T_sum);
+    std::cout << "total " <<Pt*PlaqScale<<std::endl;
+  }  
+
+  TComplex Tp = sum(Plaq);
+  Complex p  = TensorRemove(Tp);
+  std::cout << "calculated plaquettes " <<p*PlaqScale<<std::endl;
+
+
+  Complex LinkTraceScale(1.0/vol/4.0/3.0);
+  TComplex Tl = sum(LinkTrace);
+  Complex l  = TensorRemove(Tl);
+  std::cout << "calculated link trace " <<l*LinkTraceScale<<std::endl;
+
+  sumBlocks(cPlaq,Plaq);
+  TComplex TcP = sum(cPlaq);
+  Complex ll= TensorRemove(TcP);
+  std::cout << "coarsened plaquettes sum to " <<ll*PlaqScale<<std::endl;
+  
+  Grid_finalize();
+}