Index: src/Potentials/Specifics/ConstantPotential.cpp
===================================================================
--- src/Potentials/Specifics/ConstantPotential.cpp	(revision 8203ce8c8111c1436927aeed91f2ccf0f8098b1e)
+++ src/Potentials/Specifics/ConstantPotential.cpp	(revision 8203ce8c8111c1436927aeed91f2ccf0f8098b1e)
@@ -0,0 +1,177 @@
+/*
+ * Project: MoleCuilder
+ * Description: creates and alters molecular systems
+ * Copyright (C)  2012 University of Bonn. All rights reserved.
+ * Please see the COPYING file or "Copyright notice" in builder.cpp for details.
+ * 
+ *
+ *   This file is part of MoleCuilder.
+ *
+ *    MoleCuilder 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.
+ *
+ *    MoleCuilder 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 MoleCuilder.  If not, see <http://www.gnu.org/licenses/>. 
+ */
+
+/*
+ * ConstantPotential.cpp
+ *
+ *  Created on: May 09, 2013
+ *      Author: heber
+ */
+
+
+// include config.h
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "CodePatterns/MemDebug.hpp"
+
+#include "ConstantPotential.hpp"
+
+#include <boost/assign/list_of.hpp> // for 'map_list_of()'
+#include <boost/bind.hpp>
+#include <boost/lambda/lambda.hpp>
+#include <cmath>
+#include <string>
+
+#include "CodePatterns/Assert.hpp"
+
+#include "FunctionApproximation/Extractors.hpp"
+#include "FunctionApproximation/TrainingData.hpp"
+#include "Potentials/helpers.hpp"
+#include "Potentials/ParticleTypeCheckers.hpp"
+
+class Fragment;
+
+// static definitions
+const ConstantPotential::ParameterNames_t
+ConstantPotential::ParameterNames =
+      boost::assign::list_of<std::string>
+      ("energy_offset") //
+    ;
+const std::string ConstantPotential::potential_token("constant");
+
+ConstantPotential::ConstantPotential(
+    const ParticleTypes_t &_ParticleTypes
+    ) :
+  EmpiricalPotential(_ParticleTypes),
+  params(parameters_t(MAXPARAMS, 0.))
+{
+  // have some decent defaults for parameter_derivative checking
+  params[energy_offset] = 0.1;
+}
+
+ConstantPotential::ConstantPotential(
+    const ParticleTypes_t &_ParticleTypes,
+    const double _energy_offset) :
+  EmpiricalPotential(_ParticleTypes),
+  params(parameters_t(MAXPARAMS, 0.))
+{
+  params[energy_offset] = _energy_offset;
+}
+
+void ConstantPotential::setParameters(const parameters_t &_params)
+{
+  const size_t paramsDim = _params.size();
+  ASSERT( paramsDim <= getParameterDimension(),
+      "ConstantPotential::setParameters() - we need not more than "
+      +toString(getParameterDimension())+" parameters.");
+  for(size_t i=0;i<paramsDim;++i)
+    params[i] = _params[i];
+
+#ifndef NDEBUG
+  parameters_t check_params(getParameters());
+  check_params.resize(paramsDim); // truncate to same size
+  ASSERT( check_params == _params,
+      "ConstantPotential::setParameters() - failed, mismatch in to be set "
+      +toString(_params)+" and set "+toString(check_params)+" params.");
+#endif
+}
+
+ConstantPotential::results_t
+ConstantPotential::operator()(
+    const arguments_t &arguments
+    ) const
+{
+  ASSERT( arguments.size() == 0,
+      "ConstantPotential::operator() - requires no argument.");
+  ASSERT( ParticleTypeChecker::checkArgumentsAgainstParticleTypes(
+      arguments, getParticleTypes()),
+      "ConstantPotential::operator() - types don't match with ones in arguments.");
+  const result_t result = params[energy_offset];
+  return std::vector<result_t>(1, result);
+}
+
+ConstantPotential::derivative_components_t
+ConstantPotential::derivative(
+    const arguments_t &arguments
+    ) const
+{
+  ASSERT( arguments.size() == 0,
+      "ConstantPotential::operator() - requires no argument.");
+  ASSERT( ParticleTypeChecker::checkArgumentsAgainstParticleTypes(
+      arguments, getParticleTypes()),
+      "ConstantPotential::operator() - types don't match with ones in arguments.");
+  derivative_components_t result(1, 0.);
+  return result;
+}
+
+ConstantPotential::results_t
+ConstantPotential::parameter_derivative(
+    const arguments_t &arguments,
+    const size_t index
+    ) const
+{
+  ASSERT( arguments.size() == 0,
+      "ConstantPotential::parameter_derivative() - requires no argument.");
+  ASSERT( ParticleTypeChecker::checkArgumentsAgainstParticleTypes(
+      arguments, getParticleTypes()),
+      "ConstantPotential::operator() - types don't match with ones in arguments.");
+  switch (index) {
+    case energy_offset:
+    {
+      // Maple result: 1
+      const result_t result = +1.;
+      return std::vector<result_t>(1, result);
+      break;
+    }
+    default:
+      break;
+  }
+  return std::vector<result_t>(1, 0.);
+}
+
+FunctionModel::extractor_t
+ConstantPotential::getFragmentSpecificExtractor() const
+{
+  Fragment::charges_t charges;
+  charges.resize(getParticleTypes().size());
+  std::transform(getParticleTypes().begin(), getParticleTypes().end(),
+      charges.begin(), boost::lambda::_1);
+  FunctionModel::extractor_t returnfunction =
+      boost::bind(&Extractors::gatherDistancesFromFragment,
+          boost::bind(&Fragment::getPositions, _1),
+          boost::bind(&Fragment::getCharges, _1),
+          charges,
+          _2);
+  return returnfunction;
+}
+
+void
+ConstantPotential::setParametersToRandomInitialValues(
+    const TrainingData &data)
+{
+  params[ConstantPotential::energy_offset] =
+      data.getTrainingOutputAverage()[0];// -1.;
+}
+
