Adding metric and the implicit steps

2025-06-16 14:57:05 +01:00 · 2017-02-21 11:30:57 +00:00
parent 97a6b61551
commit 902afcfbaf
8 changed files with 287 additions and 59 deletions
--- a/lib/qcd/utils/Metric.h
+++ b/lib/qcd/utils/Metric.h
@ -0,0 +1,121 @@
+/*************************************************************************************
+
+Grid physics library, www.github.com/paboyle/Grid
+
+Source file: ./lib/qcd/hmc/integrators/Integrator.h
+
+Copyright (C) 2015
+
+Author: Guido Cossu <guido.cossu@ed.ac.uk>
+
+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 */
+//--------------------------------------------------------------------
+#ifndef METRIC_H
+#define METRIC_H
+
+namespace Grid{
+namespace QCD{
+
+template <typename Field> 
+class Metric{
+public:
+  virtual void ImportGauge(const Field&)   = 0;
+  virtual void M(const Field&, Field&)     = 0;
+  virtual void Minv(const Field&, Field&)  = 0;
+  virtual void MInvSquareRoot(Field&) = 0;
+};
+
+
+// Need a trivial operator
+template <typename Field>
+class TrivialMetric : public Metric<Field>{
+public:
+  virtual void ImportGauge(const Field&){};
+  virtual void M(const Field& in, Field& out){
+    out = in;
+  }
+  virtual void Minv(const Field& in, Field& out){
+    out = in;
+  }
+  virtual void MInvSquareRoot(Field& P){
+    // do nothing
+  }
+
+};
+
+///////////////////////////////
+// Generalised momenta
+///////////////////////////////
+
+template <typename Implementation, typename Metric>
+class GeneralisedMomenta{
+public:
+  typedef typename Implementation::Field MomentaField;  //for readability
+
+  Metric M;
+  MomentaField Mom;
+
+  GeneralisedMomenta(GridBase* grid): Mom(grid){}
+
+
+  void MomentaDistribution(GridParallelRNG& pRNG){
+    // Generate a distribution for
+    // 1/2 P^dag G P
+    // where G = M^-1
+
+    // Generate gaussian momenta
+    Implementation::generate_momenta(Mom, pRNG);
+    // Modify the distribution with the metric
+    M.MInvSquareRoot(Mom);
+  }
+
+  void Derivative(MomentaField& in, MomentaField& der){
+    // Compute the derivative of the kinetic term
+    // with respect to the gauge field
+    MomentaField MomDer(in._grid);
+    MomentaField X(in._grid);
+
+    M.Minv(in, X); // X = G in
+    M.MDeriv(X, MomDer, DaggerNo); // MomDer = dM/dU X
+    // MomDer is just the derivative
+    MomDer = adj(X)* MomDer;
+    // Traceless Antihermitian
+    // assuming we are in the algebra
+    der = Implementation::projectForce(MomDer);
+  }
+
+  void DerivativeP(MomentaField& der){
+    M.Minv(Mom, der);
+  }
+
+};
+
+
+
+
+
+
+
+
+}
+}
+
+
+#endif //METRIC_H