adding back files to be reviewed

include/openmc/eigenvalue.h

@@ -0,0 +1,92 @@
+//! \file eigenvalue.h
+//! \brief Data/functions related to k-eigenvalue calculations
+
+#ifndef OPENMC_EIGENVALUE_H
+#define OPENMC_EIGENVALUE_H
+
+#include <array>
+#include <cstdint> // for int64_t
+#include <vector>
+
+#include "xtensor/xtensor.hpp"
+#include <hdf5.h>
+
+#include "openmc/particle.h"
+
+namespace openmc {
+
+//==============================================================================
+// Global variables
+//==============================================================================
+
+namespace simulation {
+
+extern double keff_generation; //!<  Single-generation k on each processor
+extern std::array<double, 2> k_sum; //!< Used to reduce sum and sum_sq
+extern std::vector<double> entropy; //!< Shannon entropy at each generation
+extern xt::xtensor<double, 1> source_frac; //!< Source fraction for UFS
+
+} // namespace simulation
+
+//==============================================================================
+// Non-member functions
+//==============================================================================
+
+//! Collect/normalize the tracklength keff from each process
+void calculate_generation_keff();
+
+//! Calculate mean/standard deviation of keff during active generations
+//!
+//! This function sets the global variables keff and keff_std which represent
+//! the mean and standard deviation of the mean of k-effective over active
+//! generations. It also broadcasts the value from the master process.
+void calculate_average_keff();
+
+#ifdef _OPENMP
+//! Join threadprivate fission banks into a single fission bank
+//!
+//! Note that this operation is necessarily sequential to preserve the order of
+//! the bank when using varying numbers of threads.
+void join_bank_from_threads();
+#endif
+
+//! Calculates a minimum variance estimate of k-effective
+//!
+//! The minimum variance estimate is based on a linear combination of the
+//! collision, absorption, and tracklength estimates. The theory behind this can
+//! be found in M. Halperin, "Almost linearly-optimum combination of unbiased
+//! estimates," J. Am. Stat. Assoc., 56, 36-43 (1961),
+//! doi:10.1080/01621459.1961.10482088. The implementation here follows that
+//! described in T. Urbatsch et al., "Estimation and interpretation of keff
+//! confidence intervals in MCNP," Nucl. Technol., 111, 169-182 (1995).
+//!
+//! \param[out] k_combined Estimate of k-effective and its standard deviation
+//! \return Error status
+extern "C" int openmc_get_keff(double* k_combined);
+
+//! Sample/redistribute source sites from accumulated fission sites
+void synchronize_bank();
+
+//! Calculates the Shannon entropy of the fission source distribution to assess
+//! source convergence
+void shannon_entropy();
+
+//! Determines the source fraction in each UFS mesh cell and reweights the
+//! source bank so that the sum of the weights is equal to n_particles. The
+//! 'source_frac' variable is used later to bias the production of fission sites
+void ufs_count_sites();
+
+//! Get UFS weight corresponding to particle's location
+extern "C" double ufs_get_weight(const Particle* p);
+
+//! Write data related to k-eigenvalue to statepoint
+//! \param[in] group HDF5 group
+void write_eigenvalue_hdf5(hid_t group);
+
+//! Read data related to k-eigenvalue from statepoint
+//! \param[in] group HDF5 group
+void read_eigenvalue_hdf5(hid_t group);
+
+} // namespace openmc
+
+#endif // OPENMC_EIGENVALUE_H