rpg/fts/simulator/Simulator.tpp

#ifndef RPG_SIMULATOR_TPP
#define RPG_SIMULATOR_TPP
 
/*
* PSCF - Polymer Self-Consistent Field Theory
*
* Copyright 2016 - 2022, The Regents of the University of Minnesota
* Distributed under the terms of the GNU General Public License.
*/
 
#include "Simulator.h"
#include <rpg/System.h>
#include <rpg/fts/compressor/Compressor.h>
#include <rpg/fts/compressor/CompressorFactory.h>
#include <rpg/fts/perturbation/Perturbation.h>
#include <rpg/fts/perturbation/PerturbationFactory.h>
#include <rpg/fts/ramp/Ramp.h>
#include <rpg/fts/ramp/RampFactory.h>
#include <rpg/fts/VecOpFts.h>
#include <prdc/cuda/resources.h>
#include <pscf/math/IntVec.h>
#include <util/misc/Timer.h>
#include <util/random/Random.h>
#include <util/global.h>
#include <gsl/gsl_eigen.h>
 
namespace Pscf {
namespace Rpg {
 
   using namespace Util;
 
   /*
   * Constructor.
   */
   template <int D>
   Simulator<D>::Simulator(System<D>& system)
    : random_(),
      cudaRandom_(),
      hamiltonian_(0.0),
      idealHamiltonian_(0.0),
      fieldHamiltonian_(0.0),
      perturbationHamiltonian_(0.0),
      iStep_(0),
      iTotalStep_(0),
      seed_(0),
      hasHamiltonian_(false),
      hasWc_(false),
      hasCc_(false),
      hasDc_(false),
      systemPtr_(&system),
      compressorFactoryPtr_(nullptr),
      compressorPtr_(nullptr),
      perturbationFactoryPtr_(nullptr),
      perturbationPtr_(nullptr),
      rampFactoryPtr_(nullptr),
      rampPtr_(nullptr),
      isAllocated_(false)
   {
      setClassName("Simulator");
      compressorFactoryPtr_ = new CompressorFactory<D>(system);
      perturbationFactoryPtr_ = new PerturbationFactory<D>(*this);
      rampFactoryPtr_ = new RampFactory<D>(*this);
   }
 
   /*
   * Destructor.
   */
   template <int D>
   Simulator<D>::~Simulator()
   {
      if (compressorFactoryPtr_) {
         delete compressorFactoryPtr_;
      }
      if (compressorPtr_) {
         delete compressorPtr_;
      }
      if (perturbationFactoryPtr_) {
         delete perturbationFactoryPtr_;
      }
      if (perturbationPtr_) {
         delete perturbationPtr_;
      }
      if (rampFactoryPtr_) {
         delete rampFactoryPtr_;
      }
      if (rampPtr_) {
         delete rampPtr_;
      }
   }
 
   /*
   * Allocate required memory.
   */
   template <int D>
   void Simulator<D>::allocate()
   {
      UTIL_CHECK(!isAllocated_);
 
      const int nMonomer = system().mixture().nMonomer();
 
      // Allocate projected chi matrix chiP_ and associated arrays
      chiP_.allocate(nMonomer, nMonomer);
      chiEvals_.allocate(nMonomer);
      chiEvecs_.allocate(nMonomer, nMonomer);
      sc_.allocate(nMonomer);
 
      // Allocate memory for eignevector components of w and c fields
      wc_.allocate(nMonomer);
      cc_.allocate(nMonomer);
      const IntVec<D> dimensions = system().domain().mesh().dimensions();
      for (int i = 0; i < nMonomer; ++i) {
         wc_[i].allocate(dimensions);
         cc_[i].allocate(dimensions);
      }
 
      // Allocate memory for components of d (functional derivative)
      dc_.allocate(nMonomer-1);
      for (int i = 0; i < nMonomer - 1; ++i) {
         dc_[i].allocate(dimensions);
      }
 
      // Allocate memory for single eigenvector components of w
      // after constant shift
      wcs_.allocate(dimensions);
 
      // Allocate state_, if necessary.
      if (!state_.isAllocated) {
         state_.allocate(nMonomer, dimensions);
      }
 
      isAllocated_ = true;
   }
 
   /*
   * Virtual function - this version is only used for testing.
   */
   template <int D>
   void Simulator<D>::readParameters(std::istream &in)
   {
      readRandomSeed(in);
 
      #if 0
      // Optionally random seed
      seed_ = 0;
      readOptional(in, "seed", seed_);
 
      // Set random number generator seed.
      // Default value seed_ = 0 uses clock time.
      random().setSeed(seed_);
      cudaRandom().setSeed(seed_);
      #endif
 
      bool isEnd = false;
 
      // Read required Compressor block
      readCompressor(in, isEnd);
 
      // Optionally read a Perturbation
      readPerturbation(in, isEnd);
 
      // Optionally read a Ramp
      readRamp(in, isEnd);
   }
 
   /*
   * Perform a field theoretic simulation of nStep steps.
   */
   template <int D>
   void Simulator<D>::simulate(int nStep)
   {  UTIL_THROW("Error: Unimplemented function Simulator<D>::simulate"); }
 
   /*
   * Open, read and analyze a trajectory file
   */
   template <int D>
   void Simulator<D>::analyze(int min, int max,
                              std::string classname,
                              std::string filename)
   {  UTIL_THROW("Error: Unimplemented function Simulator<D>::analyze"); }
 
   /*
   * Compute field theoretic Hamiltonian H[W].
   */
   template <int D>
   void Simulator<D>::computeHamiltonian()
   {
      UTIL_CHECK(isAllocated_);
      UTIL_CHECK(system().w().hasData());
      UTIL_CHECK(system().hasCFields());
      UTIL_CHECK(hasWc_);
      hasHamiltonian_ = false;
 
      Mixture<D> const & mixture = system().mixture();
      Domain<D> const & domain = system().domain();
 
      const int nMonomer = mixture.nMonomer();
      const int meshSize = domain.mesh().size();
 
      const int np = mixture.nPolymer();
      const int ns = mixture.nSolvent();
      double phi, mu;
 
      // Compute polymer ideal gas contributions to lnQ
      double lnQ = 0.0;
      if (np > 0) {
         Polymer<D> const * polymerPtr;
         double length;
         for (int i = 0; i < np; ++i) {
            polymerPtr = &mixture.polymer(i);
            phi = polymerPtr->phi();
            mu = polymerPtr->mu();
            length = polymerPtr->length();
            // Recall: mu = ln(phi/q)
            if (phi > 1.0E-08) {
               lnQ += phi*( -mu + 1.0 )/length;
            }
         }
      }
 
      // Compute solvent ideal gas contributions to lnQ
      if (ns > 0) {
         Solvent<D> const * solventPtr;
         double size;
         for (int i = 0; i < ns; ++i) {
            solventPtr = &mixture.solvent(i);
            phi = solventPtr->phi();
            mu = solventPtr->mu();
            size = solventPtr->size();
            // Recall: mu = ln(phi/q)
            if (phi > 1.0E-8) {
               lnQ += phi*( -mu + 1.0 )/size;
            }
         }
      }
 
      // Add average of pressure field wc_[nMonomer-1] to lnQ
      double sum_xi = Reduce::sum(wc_[nMonomer-1]);
      lnQ += sum_xi/double(meshSize);
 
      // lnQ now contains a value per monomer
 
      // Initialize field contribution HW
 
      // Compute quadratic field contribution to HW
      double HW = 0.0;
      double prefactor, s;
      int j;
      for (j = 0; j < nMonomer - 1; ++j) {
         prefactor = -0.5*double(nMonomer)/chiEvals_[j];
         // Obtain constant shift
         s = sc_[j];
         // Subtract of constant shift s
         VecOp::subVS(wcs_, wc_[j], s);
         // Compute quadratic field contribution to HW
         double wSqure = 0;
         wSqure = Reduce::innerProduct(wcs_, wcs_);
         HW += prefactor * wSqure;
      }
 
      // Normalize HW to equal a value per monomer
      HW /= double(meshSize);
 
      // Add constant term K/2 per monomer (K=s=e^{T}chi e/M^2)
      HW += 0.5*sc_[nMonomer - 1];
 
      // Compute number of monomers in the system (nMonomerSystem)
      const double vSystem  = domain.unitCell().volume();
      const double vMonomer = mixture.vMonomer();
      const double nMonomerSystem = vSystem / vMonomer;
 
      // Compute final Hamiltonian components
      fieldHamiltonian_ = nMonomerSystem * HW;
      idealHamiltonian_ = -1.0 * nMonomerSystem * lnQ;
      hamiltonian_ = idealHamiltonian_ + fieldHamiltonian_;
 
      if (hasPerturbation()) {
        perturbationHamiltonian_ = perturbation().hamiltonian(hamiltonian_);
        hamiltonian_ += perturbationHamiltonian_;
      } else {
        perturbationHamiltonian_ = 0.0;
      }
 
      hasHamiltonian_ = true;
   }
 
   template <int D>
   void Simulator<D>::analyzeChi()
   {
      UTIL_CHECK(isAllocated_);
 
      const int nMonomer = system().mixture().nMonomer();
      DMatrix<double> const & chi = system().interaction().chi();
      double d = 1.0/double(nMonomer);
      int i, j, k;
 
      // Compute orthogonal projection matrix P
      DMatrix<double> P;
      P.allocate(nMonomer, nMonomer);
      for (i = 0; i < nMonomer; ++i) {
         for (j = 0; j < nMonomer; ++j) {
            P(i,j) = -d;
         }
         P(i,i) += 1.0;
      }
 
      // Compute T = chi*P (temporary matrix)
      DMatrix<double> T;
      T.allocate(nMonomer, nMonomer);
      for (i = 0; i < nMonomer; ++i) {
         for (j = 0; j < nMonomer; ++j) {
            T(i, j) = 0.0;
            for (k = 0; k < nMonomer; ++k) {
               T(i,j) += chi(i,k)*P(k,j);
            }
         }
      }
 
      // Compute chiP = = P*chi*P = P*T
      DMatrix<double> chiP;
      chiP.allocate(nMonomer, nMonomer);
      for (i = 0; i < nMonomer; ++i) {
         for (j = 0; j < nMonomer; ++j) {
            chiP(i, j) = 0.0;
            for (k = 0; k < nMonomer; ++k) {
               chiP(i,j) += P(i,k)*T(k,j);
            }
         }
      }
 
      // Eigenvalue calculations use data structures and
      // functions from the Gnu Scientific Library (GSL)
 
      // Allocate GSL matrix A that will hold a copy of chiP
      gsl_matrix* A = gsl_matrix_alloc(nMonomer, nMonomer);
 
      // Copy DMatrix<double> chiP to gsl_matrix A
      for (i = 0; i < nMonomer; ++i) {
         for (j = 0; j < nMonomer; ++j) {
            gsl_matrix_set(A, i, j, chiP(i, j));
         }
      }
 
      // Compute eigenvalues and eigenvectors of chiP (or A)
      gsl_eigen_symmv_workspace* work = gsl_eigen_symmv_alloc(nMonomer);
      gsl_vector* Avals = gsl_vector_alloc(nMonomer);
      gsl_matrix* Avecs = gsl_matrix_alloc(nMonomer, nMonomer);
      int error;
      error = gsl_eigen_symmv(A, Avals, Avecs, work);
      UTIL_CHECK(error == 0);
 
      // Requirements:
      // - A has exactly one zero eigenvalue, with eigenvector (1,...,1)
      // - All other eigenvalues must be negative.
 
      // Copy eigenpairs with non-null eigenvalues
      int iNull = -1;  // index for null eigenvalue
      int nNull =  0;  // number of null eigenvalue
      k = 0;           // re-ordered index for non-null eigenvalue
      double val;
      for (i = 0; i < nMonomer; ++i) {
         val = gsl_vector_get(Avals, i);
         if (std::abs(val) < 1.0E-8) {
            ++nNull;
            iNull = i;
            UTIL_CHECK(nNull <= 1);
         } else {
            chiEvals_[k] = val;
            UTIL_CHECK(val < 0.0);
            for (j = 0; j < nMonomer; ++j) {
               chiEvecs_(k, j) = gsl_matrix_get(Avecs, j, i);
            }
            if (chiEvecs_(k, 0) < 0.0) {
               for (j = 0; j < nMonomer; ++j) {
                  chiEvecs_(k, j) = -chiEvecs_(k, j);
               }
            }
            ++k;
         }
      }
      UTIL_CHECK(nNull == 1);
      UTIL_CHECK(iNull >= 0);
 
      // Set eigenpair with zero eigenvalue
      i = nMonomer - 1;
      chiEvals_[i] = 0.0;
      for (j = 0; j < nMonomer; ++j) {
         chiEvecs_(i, j) = gsl_matrix_get(Avecs, j, iNull);
      }
      if (chiEvecs_(i, 0) < 0) {
         for (j = 0; j < nMonomer; ++j) {
            chiEvecs_(i, j) = -chiEvecs_(i, j);
         }
      }
 
      // Normalize all eigenvectors so that the sum of squares = nMonomer
      double vec, norm, prefactor;
      for (i = 0;  i < nMonomer; ++i) {
         norm = 0.0;
         for (j = 0;  j < nMonomer; ++j) {
            vec = chiEvecs_(i, j);
            norm += vec*vec;
         }
         prefactor = sqrt( double(nMonomer)/norm );
         for (j = 0;  j < nMonomer; ++j) {
            chiEvecs_(i, j) *= prefactor;
         }
      }
 
      // Check final eigenvector is (1, ..., 1)
      for (j = 0; j < nMonomer; ++j) {
         UTIL_CHECK(std::abs(chiEvecs_(nMonomer-1, j) - 1.0) < 1.0E-8);
      }
 
      // Compute vector s in monomer basis
      DArray<double> s;
      s.allocate(nMonomer);
      for (i = 0; i < nMonomer; ++i) {
         s[i] = 0.0;
         for (j = 0; j < nMonomer; ++j) {
           s[i] += chi(i,j);
         }
         s[i] = s[i]/double(nMonomer);
      }
 
      // Compute components of s in eigenvector basis -> sc_
      for (i = 0; i < nMonomer; ++i) {
         sc_[i] = 0.0;
         for (j = 0; j < nMonomer; ++j) {
            sc_[i] += chiEvecs_(i,j)*s[j];
         }
         sc_[i] = sc_[i]/double(nMonomer);
      }
 
      #if 0
      // Debugging output
      for (i = 0; i < nMonomer; ++i) {
         Log::file() << "Eigenpair " << i << "\n";
         Log::file() << "value  =  " << chiEvals_[i] << "\n";
         Log::file() << "vector = [ ";
         for (j = 0; j < nMonomer; ++j) {
            Log::file() << chiEvecs_(i, j) << "   ";
         }
         Log::file() << "]\n";
         Log::file() << " sc[i] = " << sc_[i] << std::endl;
      }
      #endif
 
   }
 
   /*
   * Compute the eigenvector components of the w fields, using the
   * eigenvectors chiEvecs_ of the projected chi matrix as a basis.
   */
   template <int D>
   void Simulator<D>::computeWc()
   {
      UTIL_CHECK(isAllocated_);
 
      const int nMonomer = system().mixture().nMonomer();
      int i,j;
 
      // Loop over eigenvectors (i is an eigenvector index)
      for (i = 0; i < nMonomer; ++i) {
 
         // Loop over grid points to zero out field wc_[i]
         RField<D>& Wc = wc_[i];
         VecOp::eqS(Wc, 0.0);
 
         // Loop over monomer types (j is a monomer index)
         for (j = 0; j < nMonomer; ++j) {
            cudaReal vec;
            vec = (cudaReal) chiEvecs_(i, j)/nMonomer;
 
            // Loop over grid points
            VecOp::addEqVc(Wc, system().w().rgrid(j), vec);
         }
      }
 
      #if 0
      // Debugging output
      std::string filename = "wc";
      system().fieldIo().writeFieldsRGrid(filename, wc_,
                                          system().domain().unitCell());
      #endif
 
      hasWc_ = true;
   }
 
   /*
   * Compute the eigenvector components of the c-fields, using the
   * eigenvectors chiEvecs_ of the projected chi matrix as a basis.
   */
   template <int D>
   void Simulator<D>::computeCc()
   {
      // Preconditions
      UTIL_CHECK(isAllocated_);
      UTIL_CHECK(system().w().hasData());
      UTIL_CHECK(system().hasCFields());
 
      const int nMonomer = system().mixture().nMonomer();
      int i, j;
 
      // Loop over eigenvectors (i is an eigenvector index)
      for (i = 0; i < nMonomer; ++i) {
 
         // Set cc_[i] to zero
         RField<D>& Cc = cc_[i];
         VecOp::eqS(Cc, 0.0);
 
         // Loop over monomer types
         for (j = 0; j < nMonomer; ++j) {
            cudaReal vec;
            vec = (cudaReal)chiEvecs_(i, j);
 
            // Loop over grid points
            VecOp::addEqVc(Cc, system().c().rgrid(j), vec);
         }
      }
 
      #if 0
      // Debugging output
      std::string filename = "cc";
      system().fieldIo().writeFieldsRGrid(filename, cc_,
                                          system().domain().unitCell());
      #endif
 
      hasCc_ = true;
   }
 
   /*
   * Compute d fields, i.e., functional derivatives of H[W].
   */
   template <int D>
   void Simulator<D>::computeDc()
   {
      // Preconditions
      UTIL_CHECK(isAllocated_);
      if (!hasWc_) computeWc();
      if (!hasCc_) computeCc();
 
      // Local constants and variables
      const int nMonomer = system().mixture().nMonomer();
      const double vMonomer = system().mixture().vMonomer();
      const double a = 1.0/vMonomer;
      double b, s;
      int i;
 
      // Loop over composition eigenvectors (exclude the last)
      for (i = 0; i < nMonomer - 1; ++i) {
         RField<D>& Dc = dc_[i];
         RField<D> const & Wc = wc_[i];
         RField<D> const & Cc = cc_[i];
         b = -1.0*double(nMonomer)/chiEvals_[i];
         s = sc_[i];
 
         // Loop over grid points
         VecOpFts::computeDField(Dc, Wc, Cc, a, b, s);
      }
 
      // Add derivatives arising from a perturbation (if any).
      if (hasPerturbation()) {
         perturbation().incrementDc(dc_);
      }
 
      hasDc_ = true;
   }
 
   /*
   * Save the current state prior to a next move.
   *
   * Invoked before each move.
   */
   template <int D>
   void Simulator<D>::saveState()
   {
      UTIL_CHECK(system().w().hasData());
      UTIL_CHECK(hasWc());
      UTIL_CHECK(state_.isAllocated);
      UTIL_CHECK(!state_.hasData);
 
      // Set fields
      int nMonomer = system().mixture().nMonomer();
 
      // Set field components
      for (int i = 0; i < nMonomer; ++i) {
         VecOp::eqV(state_.w[i], system().w().rgrid(i));
         VecOp::eqV(state_.wc[i], wc_[i]);
      }
 
      // Save cc based on ccSavePolicy
      if (state_.needsCc) {
         UTIL_CHECK(hasCc());
         for (int i = 0; i < nMonomer; ++i) {
            VecOp::eqV(state_.cc[i], cc_[i]);
         }
      }
 
      // Save dc based on dcSavePolicy
      if (state_.needsDc) {
         UTIL_CHECK(hasDc());
         for (int i = 0; i < nMonomer - 1; ++i) {
            VecOp::eqV(state_.dc[i], dc_[i]);
         }
      }
 
      // Save Hamiltonian based on hamiltonianSavePolicy
      if (state_.needsHamiltonian){
         UTIL_CHECK(hasHamiltonian());
         state_.hamiltonian  = hamiltonian();
         state_.idealHamiltonian  = idealHamiltonian();
         state_.fieldHamiltonian  = fieldHamiltonian();
         state_.perturbationHamiltonian  = perturbationHamiltonian();
      }
 
      if (hasPerturbation()) {
         perturbation().saveState();
      }
 
      state_.hasData = true;
   }
 
   /*
   * Restore a saved fts state.
   *
   * Invoked after an attempted Monte-Carlo move is rejected
   * or an fts move fails to converge
   */
   template <int D>
   void Simulator<D>::restoreState()
   {
      UTIL_CHECK(state_.isAllocated);
      UTIL_CHECK(state_.hasData);
      int nMonomer = system().mixture().nMonomer();
      int meshSize = system().domain().mesh().size();
 
      // Restore fields
      system().setWRGrid(state_.w);
 
      // Restore Hamiltonian and components
      if (state_.needsHamiltonian){
         hamiltonian_ = state_.hamiltonian;
         idealHamiltonian_ = state_.idealHamiltonian;
         fieldHamiltonian_ = state_.fieldHamiltonian;
         perturbationHamiltonian_ = state_.perturbationHamiltonian;
         hasHamiltonian_ = true;
      }
 
      for (int i = 0; i < nMonomer; ++i) {
         VecOp::eqV(wc_[i], state_.wc[i]);
      }
      hasWc_ = true;
 
      if (state_.needsCc) {
         for (int i = 0; i < nMonomer; ++i) {
            VecOp::eqV(cc_[i], state_.cc[i]);
         }
         hasCc_ = true;
      }
 
      if (state_.needsDc) {
         for (int i = 0; i < nMonomer - 1; ++i) {
            VecOp::eqV(dc_[i], state_.dc[i]);
         }
         hasDc_ = true;
      }
 
      if (hasPerturbation()) {
         perturbation().restoreState();
      }
 
      state_.hasData = false;
   }
 
   /*
   * Clear the saved Monte-Carlo state.
   *
   * Invoked when an attempted Monte-Carlo move is accepted.
   */
   template <int D>
   void Simulator<D>::clearState()
   {  state_.hasData = false; }
 
   /*
   * Output all timer results.
   */
   template<int D>
   void Simulator<D>::outputTimers(std::ostream& out)
   {
      outputMdeCounter(out);
      compressor().outputTimers(out);
   }
 
   /*
   * Output modified diffusion equation (MDE) counter.
   */
   template<int D>
   void Simulator<D>::outputMdeCounter(std::ostream& out)
   {
      //out << std::endl;
      out << "MDE counter   "
          << compressor().mdeCounter() << std::endl;
      out << std::endl;
   }
 
   /*
   * Clear all timers.
   */
   template<int D>
   void Simulator<D>::clearTimers()
   {
      UTIL_CHECK(hasCompressor());
      compressor().clearTimers();
   }
 
   // Protected Functions
 
   /*
   * Read random seed and initialize random number generators.
   */
   template <int D>
   void Simulator<D>::readRandomSeed(std::istream &in)
   {
      // Optionally random seed
      seed_ = 0;
      readOptional(in, "seed", seed_);
 
      // Set seed values for both random number generators
      // Default value seed_ = 0 uses clock time.
      random().setSeed(seed_);
      cudaRandom().setSeed(seed_);
   }
 
   /*
   * Read the required Compressor parameter file block.
   */
   template<int D>
   void Simulator<D>::readCompressor(std::istream& in, bool& isEnd)
   {
      if (!isEnd) {
         UTIL_CHECK(!hasCompressor());
         UTIL_CHECK(compressorFactoryPtr_);
         std::string className;
         compressorPtr_ =
            compressorFactory().readObjectOptional(in, *this,
                                                   className, isEnd);
      }
      if (!hasCompressor() && ParamComponent::echo()) {
         Log::file() << indent() << "  Compressor{ [absent] }\n";
      }
   }
 
   // Functions related to an associated Perturbation
 
   /*
   * Optionally read a Perturbation parameter file block.
   */
   template<int D>
   void Simulator<D>::readPerturbation(std::istream& in, bool& isEnd)
   {
      if (!isEnd) {
         UTIL_CHECK(!hasPerturbation());
         UTIL_CHECK(perturbationFactoryPtr_);
         std::string className;
         perturbationPtr_ =
            perturbationFactory().readObjectOptional(in, *this,
                                                     className, isEnd);
      }
      if (!hasPerturbation() && ParamComponent::echo()) {
         Log::file() << indent() << "  Perturbation{ [absent] }\n";
      }
   }
 
   /*
   * Set the associated Perturbation<D> object.
   */
   template<int D>
   void Simulator<D>::setPerturbation(Perturbation<D>* ptr)
   {
      UTIL_CHECK(ptr != 0);
      perturbationPtr_ = ptr;
   }
 
   /*
   * Optionally read a parameter file block for an associated Ramp.
   */
   template<int D>
   void Simulator<D>::readRamp(std::istream& in, bool& isEnd)
   {
      if (!isEnd) {
         UTIL_CHECK(!hasRamp());
         UTIL_CHECK(rampFactoryPtr_);
         std::string className;
         rampPtr_ =
            rampFactory().readObjectOptional(in, *this, 
                                             className, isEnd);
      }
      if (!hasRamp() && ParamComponent::echo()) {
         Log::file() << indent() << "  Ramp{ [absent] }\n";
      }
   }
 
   /*
   * Set the associated Ramp<D> object.
   */
   template<int D>
   void Simulator<D>::setRamp(Ramp<D>* ptr)
   {
      UTIL_CHECK(ptr != 0);
      rampPtr_ = ptr;
   }
 
}
}
#endif