|| || || || || || || ||

---

Reduce.h

Go to the documentation of this file.

#ifndef Impala_Util_Mpi_Reduce_h
#define Impala_Util_Mpi_Reduce_h

#include "Link/Mpi/MpiFuncs.h"
#include <vector>

namespace Impala
{
namespace Util
{
namespace Mpi
{

void Reduce(std::vector<double>& v)
{
#ifdef MPI_USED
    MPI_Barrier(MPI_COMM_WORLD);
    int gridSize = v.size();
    // note: copying might be a problem for large vectors...
    double* grid = new double[gridSize];
    int i;
    for(i=0 ; i<gridSize ; ++i)
        grid[i] = v[i];

    double* reducedGrid = 0;
    if(Link::Mpi::MyId() == 0)
        reducedGrid = new double[gridSize];
    MPI_Reduce(grid, reducedGrid, gridSize, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);
    if(Link::Mpi::MyId() == 0)
    {
        for(i=0 ; i<gridSize ; ++i)
            v[i] = reducedGrid[i];
        delete reducedGrid;
    }
#endif
}

} //namespace
} //namespace
} //namespace

#endif

---