PartialFraction Hw with Zolo and Tanh approx converged under CG and passed EO breakdown

and hermiticity tests.

lib/qcd/action/fermion/OverlapWilsonPartialFractionZolotarevFermion.h

@@ -0,0 +1,44 @@
+#ifndef OVERLAP_WILSON_PARTFRAC_ZOLOTAREV_FERMION_H
+#define OVERLAP_WILSON_PARTFRAC_ZOLOTAREV_FERMION_H
+
+#include <Grid.h>
+
+namespace Grid {
+
+  namespace QCD {
+
+    class OverlapWilsonPartialFractionZolotarevFermion : public PartialFractionFermion5D
+    {
+    public:
+
+      virtual void   Instantiatable(void){};
+      // Constructors
+    OverlapWilsonPartialFractionZolotarevFermion(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
+      PartialFractionFermion5D(_Umu,
+			       FiveDimGrid,
+			       FiveDimRedBlackGrid,
+			       FourDimGrid,
+			       FourDimRedBlackGrid,_mass,_M5)
+	{
+	  assert((Ls&0x1)==1); // Odd Ls required
+
+	  int nrational=Ls;// Odd rational order
+	  RealD eps = lo/hi;
+
+	  Approx::zolotarev_data *zdata = Approx::zolotarev(eps,nrational,0);
+	  SetCoefficientsZolotarev(hi,zdata);
+	  Approx::zolotarev_free(zdata);
+
+	}
+    };
+  }
+}
+#endif