From a741e7b9baf09cf450c28df074aa670202eb7e1f Mon Sep 17 00:00:00 2001
From: Guido Cossu <guido.cossu@ed.ac.uk>
Date: Wed, 2 May 2018 11:05:47 +0100
Subject: [PATCH] Added ExpScalar observable

---
 lib/qcd/QCD.h                        |  2 +-
 lib/qcd/modules/ObservableModules.h  | 14 +++++
 lib/qcd/observables/exp_scalar.h     | 80 ++++++++++++++++++++++++++++
 lib/qcd/observables/hmc_observable.h |  2 +-
 lib/version.h                        |  1 +
 tests/hmc/Test_hmc_shGordonAction.cc |  6 +++
 6 files changed, 103 insertions(+), 2 deletions(-)
 create mode 100644 lib/qcd/observables/exp_scalar.h
 create mode 100644 lib/version.h

diff --git a/lib/qcd/QCD.h b/lib/qcd/QCD.h
index e1e38e82..16f82af1 100644
--- a/lib/qcd/QCD.h
+++ b/lib/qcd/QCD.h
@@ -51,7 +51,7 @@ namespace QCD {
 
     static const int Nc=3;
     static const int Ns=4;
-    static const int Nd=4;
+    static const int Nd=2;
     static const int Nhs=2; // half spinor
     static const int Nds=8; // double stored gauge field
     static const int Ngp=2; // gparity index range
diff --git a/lib/qcd/modules/ObservableModules.h b/lib/qcd/modules/ObservableModules.h
index fbffc236..3a092e72 100644
--- a/lib/qcd/modules/ObservableModules.h
+++ b/lib/qcd/modules/ObservableModules.h
@@ -92,6 +92,20 @@ class PlaquetteMod: public ObservableModule<PlaquetteLogger<Impl>, NoParameters>
   PlaquetteMod(): ObsBase(NoParameters()){}
 };
 
+template < class Impl >
+class ExpScalarMod: public ObservableModule<ExpScalarLogger<Impl>, ExpScalarParameters>{
+  typedef ObservableModule<ExpScalarLogger<Impl>, ExpScalarParameters> ObsBase;
+  using ObsBase::ObsBase; // for constructors
+
+  // acquire resource
+  virtual void initialize(){
+    this->ObservablePtr.reset(new ExpScalarLogger<Impl>(this->Par_));
+  }
+  public:
+  ExpScalarMod(ExpScalarParameters P): ObsBase(P){}
+  ExpScalarMod():ObsBase(){};
+};
+
 template < class Impl >
 class PolyakovMod: public ObservableModule<PolyakovLogger<Impl>, NoParameters>{
   typedef ObservableModule<PolyakovLogger<Impl>, NoParameters> ObsBase;
diff --git a/lib/qcd/observables/exp_scalar.h b/lib/qcd/observables/exp_scalar.h
new file mode 100644
index 00000000..cc41d563
--- /dev/null
+++ b/lib/qcd/observables/exp_scalar.h
@@ -0,0 +1,80 @@
+/*************************************************************************************
+
+Grid physics library, www.github.com/paboyle/Grid
+
+Source file: ./lib/qcd/modules/exp_scalar.h
+
+Copyright (C) 2018
+
+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 HMC_EXP_SCALAR_H
+#define HMC_EXP_SCALAR_H
+
+namespace Grid {
+namespace QCD {
+
+struct ExpScalarParameters : Serializable {
+    GRID_SERIALIZABLE_CLASS_MEMBERS(ExpScalarParameters,
+    double, a)
+
+    ExpScalarParameters(double _a = 0.0):a(_a){}
+
+    template < class ReaderClass >
+    ExpScalarParameters(Reader<ReaderClass>& Reader){
+        read(Reader, "ExpScalar", *this);  
+    }  
+};
+
+template <class Impl>
+class ExpScalarLogger : public HmcObservable<typename Impl::Field> {
+  ExpScalarParameters Pars;
+ public:
+
+  // necessary for HmcObservable compatibility
+  typedef typename Impl::Field Field;
+
+  ExpScalarLogger(double _a):Pars(_a){}
+
+  ExpScalarLogger(ExpScalarParameters P):Pars(P){}
+
+  void TrajectoryComplete(int traj, typename Impl::Field &U,
+                          GridSerialRNG &sRNG,
+                          GridParallelRNG &pRNG) {
+
+    double e = sum(trace(exp(Pars.a*U)));
+
+    int def_prec = std::cout.precision();
+
+    std::cout << GridLogMessage
+        << std::setprecision(std::numeric_limits<Real>::digits10 + 1)
+        << "ExpScalar: [ " << traj << " ] "<< e << std::endl;
+
+    std::cout.precision(def_prec);
+
+  }
+};
+
+}  // namespace QCD
+}  // namespace Grid
+
+#endif  // HMC_PLAQUETTE_H
diff --git a/lib/qcd/observables/hmc_observable.h b/lib/qcd/observables/hmc_observable.h
index fcf11774..222e0ff1 100644
--- a/lib/qcd/observables/hmc_observable.h
+++ b/lib/qcd/observables/hmc_observable.h
@@ -46,6 +46,6 @@ class HmcObservable {
 #include "plaquette.h"
 #include "topological_charge.h"
 #include "polyakov_loop.h"
-
+#include "exp_scalar.h"
 
 #endif  //  HMC_OBSERVABLE_H
diff --git a/lib/version.h b/lib/version.h
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/lib/version.h
@@ -0,0 +1 @@
+
diff --git a/tests/hmc/Test_hmc_shGordonAction.cc b/tests/hmc/Test_hmc_shGordonAction.cc
index ada82c1f..7cbb758e 100644
--- a/tests/hmc/Test_hmc_shGordonAction.cc
+++ b/tests/hmc/Test_hmc_shGordonAction.cc
@@ -91,6 +91,12 @@ int main(int argc, char **argv) {
   RNGModuleParameters RNGpar(Reader);
   TheHMC.Resources.SetRNGSeeds(RNGpar);
 
+  // Some online observable measurements
+  typedef ExpScalarMod<HMCWrapper::ImplPolicy> ExpObs;
+  ExpScalarParameters ExpParams(Reader);
+  TheHMC.Resources.AddObservable<ExpObs>(ExpParams);
+  ///////////////////////////////////////////
+
   // Real Scalar sh-Gordon action
   ScalarActionParameters SPar(Reader);
   shGordonActionR Saction(SPar.mass_squared, SPar.g);