qoiavgplaquette.cc

#include "qoiavgplaquette.hh"
/** @file qoiavgplaquette.cc
 * @brief Implementation of qoiavgplaquette.hh
 */

/* Evaluate QoI */
const double
QoIAvgPlaquette::evaluate(const std::shared_ptr<SampleState> phi_state) {
  // lambda function for working out linear index of link
  if (phi_state->data.size() != 2 * Mt_lat * Mx_lat) {
    mpi_parallel::cout
        << "ERROR: Evaluating QoIAvgPlaquette on state of wrong size."
        << std::endl;
    mpi_exit(EXIT_FAILURE);
  }
  double S_plaq = 0.0;
  for (int i = 0; i < Mt_lat; ++i) {
    for (int j = 0; j < Mx_lat; ++j) {
      double theta = phi_state->data[lattice->link_cart2lin(i, j, 0)] +
                     phi_state->data[lattice->link_cart2lin(i + 1, j, 1)] -
                     phi_state->data[lattice->link_cart2lin(i, j + 1, 0)] -
                     phi_state->data[lattice->link_cart2lin(i, j, 1)];
      S_plaq += cos(theta);
    }
  }
  return S_plaq / (Mx_lat * Mt_lat);
}