RandNumGen.cpp

/*
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 *
 * SUPPORT OPEN SCIENCE!  If you use OpenMD or its source code in your
 * research, please cite the appropriate papers when you publish your
 * work.  Good starting points are:
 *
 * [1] Meineke, et al., J. Comp. Chem. 26, 252-271 (2005).
 * [2] Fennell & Gezelter, J. Chem. Phys. 124, 234104 (2006).
 * [3] Sun, Lin & Gezelter, J. Chem. Phys. 128, 234107 (2008).
 * [4] Vardeman, Stocker & Gezelter, J. Chem. Theory Comput. 7, 834 (2011).
 * [5] Kuang & Gezelter, Mol. Phys., 110, 691-701 (2012).
 * [6] Lamichhane, Gezelter & Newman, J. Chem. Phys. 141, 134109 (2014).
 * [7] Lamichhane, Newman & Gezelter, J. Chem. Phys. 141, 134110 (2014).
 * [8] Bhattarai, Newman & Gezelter, Phys. Rev. B 99, 094106 (2019).
 */
 
#include "utils/RandNumGen.hpp"
 
#ifdef IS_MPI
#include <mpi.h>
#endif
 
#include <numeric>
#include <random>
#include <vector>
 
namespace OpenMD {
  namespace Utils {
 
    RandNumGen::RandNumGen(result_type seed) {
      result_type result;
      int nProcessors {1};
 
#ifdef IS_MPI
      int worldRank {};
      MPI_Status status;
 
      MPI_Comm_rank(MPI_COMM_WORLD, &worldRank);
      MPI_Comm_size(MPI_COMM_WORLD, &nProcessors);
 
      if (worldRank == 0) {
#endif
        std::vector<result_type> initalSequence(nProcessors);
        std::iota(initalSequence.begin(), initalSequence.end(), seed);
 
        // Generate the seed_seq to initialize the RNG on each processor
        std::seed_seq seq(initalSequence.begin(), initalSequence.end());
        std::vector<result_type> seeds(nProcessors);
        seq.generate(seeds.begin(), seeds.end());
 
        result = seeds[0];
 
#ifdef IS_MPI
        for (int index {1}; index < nProcessors; ++index)
          MPI_Send(&seeds[index], 1, MPI_UINT32_T, index, 10, MPI_COMM_WORLD);
      } else {
        MPI_Recv(&result, 1, MPI_UINT32_T, 0, 10, MPI_COMM_WORLD, &status);
      }
#endif
 
      engine = std::mt19937(result);
    }
  }  // namespace Utils
}  // namespace OpenMD