historylist.hpp

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/**
 * @file historylist.hpp
 * @author Moritz Gubler (moritz.gubler@unibas.ch)
 * @brief Implementation of the SQNM method. More informations about the algorithm can be found here: https://aip.scitation.org/doi/10.1063/1.4905665
 * @date 2022-07-13
 * 
 */
 
#ifndef HISTORYLIST_HPP
#define HISTORYLIST_HPP
#include <Eigen/Dense>
 
namespace vcsqnm {
 
namespace hlist_space{
  class HistoryList {
    private:
    int i_count = 0;
    int nhistx;
    int ndim;
    Eigen::VectorXd oldElem;
 
    public: 
 
    Eigen::MatrixXd hlist;
    Eigen::MatrixXd difflist;
    Eigen::MatrixXd normalized_difflist;
 
 
    HistoryList(int &ndim_, int &nhistx_)
    {
      nhistx = nhistx_;
      ndim = ndim_;
      hlist.resize(ndim, nhistx);
      difflist.resize(ndim, nhistx);
      normalized_difflist.resize(ndim, nhistx);
      i_count = 0;
    }
 
    int add(Eigen::VectorXd &x_in)
    {
      if (i_count < nhistx){
        hlist.col(i_count) = x_in;
        i_count += 1;
        for (int i = 1; i < i_count; i++){
          difflist.col(i-1) = hlist.col(i) - hlist.col(i - 1);
          normalized_difflist.col(i-1) = difflist.col(i-1) / difflist.col(i-1).norm();
        }
        return i_count - 1;
      } else {
        oldElem = hlist.col(0);
        for (int i = 0; i < nhistx - 1; i++){
          hlist.col(i) = hlist.col(i+1);
        }
        hlist.col(nhistx - 1) = x_in;
        // calculate difference list
        difflist.col(0) = hlist.col(0) - oldElem;
        normalized_difflist.col(0) = difflist.col(0) / difflist.col(0).norm();
        for (int i = 1; i < nhistx; i++){
          difflist.col(i) = hlist.col(i) - hlist.col(i - 1);
          normalized_difflist.col(i) = difflist.col(i) / difflist.col(i).norm();
        }
        return nhistx;
        }
      }
    };
}
 
}
 
#endif