Implementing the Hw kernel continued fraction 5d overlap cases

lib/qcd/action/fermion/OverlapWilsonContfracTanhFermion.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 OverlapWilsonContFracTanhFermion : public ContinuedFractionFermion5D
+    {
+    public:
+
+      virtual void   Instantiatable(void){};
+      // Constructors
+    OverlapWilsonContFracTanhFermion(LatticeGaugeField &_Umu,
+				     GridCartesian         &FiveDimGrid,
+				     GridRedBlackCartesian &FiveDimRedBlackGrid,
+				     GridCartesian         &FourDimGrid,
+				     GridRedBlackCartesian &FourDimRedBlackGrid,
+				     RealD _mass,RealD _M5,
+				     RealD scale) :
+      
+      // 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
+	  zdata = Approx::grid_higham(1.0,nrational);// eps is ignored for higham
+	  SetCoefficientsTanh(zdata,scale);
+	}
+    };
+  }
+}
+#endif