chi_math_mpi_03_vecops.cc

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#include "chi_math_mpi.h"
 
#include "chi_math.h"
 
namespace chi_math
{
 
/**Computes a global L2-norm*/
double Vec2NormMPI(const VecDbl& x, MPI_Comm comm)
{
  size_t n = x.size();
  double local_sum = 0.;
 
  for(size_t i = 0; i != n; i++)
    local_sum += x[i]*x[i];
 
  double global_sum;
  MPI_Allreduce(&local_sum,       //sendbuf
                &global_sum,      //recvbuf
                1, MPI_DOUBLE,     //count + datatype
                MPI_SUM,           //operation
                comm);             //communicator
 
  return sqrt(global_sum);
}
 
}//namespace chi_math