r1d/solvers/Propagator.cpp

/*
* PSCF - Polymer Self-Consistent Field
*
* Copyright 2015 - 2025, The Regents of the University of Minnesota
* Distributed under the terms of the GNU General Public License.
*/
 
#include "Propagator.h"
#include "Block.h"
#include <r1d/field/Domain.h>
 
namespace Pscf { 
namespace R1d
{
 
   using namespace Util;
 
   /*
   * Constructor.
   */
   Propagator::Propagator()
    : blockPtr_(0),
      ns_(0),
      nx_(0),
      isAllocated_(false)
   {}
 
   /*
   * Destructor.
   */
   Propagator::~Propagator()
   {}
 
   /*
   * Allocate memory used by this propagator.
   */
   void Propagator::allocate(int ns, int nx)
   {
      ns_ = ns;
      nx_ = nx;
      qFields_.allocate(ns);
      for (int i = 0; i < ns; ++i) {
         qFields_[i].allocate(nx);
      }
      isAllocated_ = true;
   }
 
   /*
   * Reallocate memory used by this propagator using new ns value.
   */
   void Propagator::reallocate(int ns)
   {
      UTIL_CHECK(isAllocated_);
      UTIL_CHECK(ns_ != ns);
      ns_ = ns;
 
      // Deallocate memory previously used by this propagator.
      // NOTE: DArray::deallocate() calls "delete [] ptr", where ptr is a 
      // pointer to the underlying C array. This will call the destructor
      // for each element in the underlying C array, freeing all memory 
      // that was allocated to the objects stored in the DArray.
      qFields_.deallocate();
 
      // Allocate memory in qFields_ using new value of ns
      qFields_.allocate(ns);
      for (int i = 0; i < ns; ++i) {
         qFields_[i].allocate(nx_);
      }
 
      setIsSolved(false);
   }
 
 
   bool Propagator::isAllocated() const
   {  return isAllocated_; }
 
   /*
   * Compute initial head q-field from final tail q-fields of sources.
   */
   void Propagator::computeHead()
   {
 
      // Reference to head of this propagator
      FieldT& qh = qFields_[0];
 
      // Initialize qh field to 1.0 at all grid points
      int ix;
      for (ix = 0; ix < nx_; ++ix) {
         qh[ix] = 1.0;
      }
 
      // Pointwise multiply tail q-fields of all sources
      for (int is = 0; is < nSource(); ++is) {
         if (!source(is).isSolved()) {
            UTIL_THROW("Source not solved in computeHead");
         }
         FieldT const& qt = source(is).tail();
         for (ix = 0; ix < nx_; ++ix) {
            qh[ix] *= qt[ix];
         }
      }
   }
 
   /*
   * Solve the modified diffusion equation for this block.
   */
   void Propagator::solve()
   {
      computeHead();
      for (int iStep = 0; iStep < ns_ - 1; ++iStep) {
         block().step(qFields_[iStep], qFields_[iStep + 1]);
      }
      setIsSolved(true);
   }
 
   /*
   * Solve the modified diffusion equation with specified initial field.
   */
   void Propagator::solve(const Propagator::FieldT& head) 
   {
      // Initialize initial (head) field
      FieldT& qh = qFields_[0];
      for (int i = 0; i < nx_; ++i) {
         qh[i] = head[i];
      }
 
      // Setup solver and solve
      for (int iStep = 0; iStep < ns_ - 1; ++iStep) {
         block().step(qFields_[iStep], qFields_[iStep + 1]);
      }
      setIsSolved(true);
   }
 
   /*
   * Integrate to calculate monomer concentration for this block
   */
   void Propagator::computeQ(double & Q)
   {
      if (!isSolved()) {
         UTIL_THROW("Propagator is not solved.");
      }
      if (!hasPartner()) {
         UTIL_THROW("Propagator has no partner set.");
      }
      if (!partner().isSolved()) {
         UTIL_THROW("Partner propagator is not solved");
      }
      FieldT const& qh = head();
      FieldT const& qt = partner().tail();
      Q = block().domain().innerProduct(qh, qt);
   }
 
}
}