Implementing the Hw kernel continued fraction 5d overlap cases

lib/qcd/action/fermion/OverlapWilsonContfracZolotarevFermion.h

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+#ifndef OVERLAP_WILSON_CAYLEY_TANH_FERMION_H
+#define OVERLAP_WILSON_CAYLEY_TANH_FERMION_H
+
+#include <Grid.h>
+
+namespace Grid {
+
+  namespace QCD {
+
+    class OverlapWilsonContFracZolotarevFermion : public ContinuedFractionFermion5D
+    {
+    public:
+
+      virtual void   Instantiatable(void){};
+      // Constructors
+    OverlapWilsonContFracZolotarevFermion(LatticeGaugeField &_Umu,
+					  GridCartesian         &FiveDimGrid,
+					  GridRedBlackCartesian &FiveDimRedBlackGrid,
+					  GridCartesian         &FourDimGrid,
+					  GridRedBlackCartesian &FourDimRedBlackGrid,
+					  RealD _mass,RealD _M5,
+					  RealD lo,RealD hi):
+      
+      // b+c=scale, b-c = 0 <=> b =c = scale/2
+      ContinuedFractionFermion5D(_Umu,
+				 FiveDimGrid,
+				 FiveDimRedBlackGrid,
+				 FourDimGrid,
+				 FourDimRedBlackGrid,_mass)
+	{
+	  assert((Ls&0x1)==1); // Odd Ls required
+
+	  int nrational=Ls-1;// Even rational order
+	  RealD eps = lo/hi;
+
+	  Approx::zolotarev_data *zdata = Approx::grid_zolotarev(eps,nrational,0);
+
+	  SetCoefficientsZolotarev(hi,zdata);
+
+	}
+    };
+  }
+}
+#endif