MPILocalDomainLimits.c File Reference

Compute local domain limites of a MPI rank. More...

#include <stdlib.h>
#include <basic.h>
#include <mpivars.h>

Go to the source code of this file.

Functions
int	MPILocalDomainLimits (int ndims, int p, void *m, int *dim_global, int *is, int *ie)

Detailed Description

Compute local domain limites of a MPI rank.

Author

Debojyoti Ghosh

Definition in file MPILocalDomainLimits.c.

Function Documentation

int MPILocalDomainLimits	(	int	ndims,
		int	p,
		void *	m,
		int *	dim_global,
		int *	is,
		int *	ie
	)

Computes the local domain limites: Given a MPI rank p, this function will compute the starting and ending indices of the local domain on this rank. These indices are global.

• The starting and ending indices are stored in preallocated integer arrays, whose elements are these indices in each spatial dimension.
• The ending index is 1 + actual last index; thus the one can write the loop as (i=start; i<end; i++) and not (i=start; i<=end; i++).

Parameters

ndims	Number of spatial dimensions
p	MPI rank
m	MPI object of type MPIVariables
dim_global	Integer array with elements as global size in each spatial dimension
is	Integer array whose elements will contain the starting index of the local domain on rank p
ie	Integer array whose elements will contain the ending index of the local domain on rank p

Definition at line 18 of file MPILocalDomainLimits.c.

{
  MPIVariables *mpi = (MPIVariables*) m;
  int          i;
  _DECLARE_IERR_;

  int ip[ndims];
  IERR MPIRanknD(ndims,p,mpi->iproc,ip); CHECKERR(ierr);

  for (i=0; i<ndims; i++) {
    int imax_local, isize, root = 0;
    imax_local = MPIPartition1D(dim_global[i],mpi->iproc[i],root );
    isize      = MPIPartition1D(dim_global[i],mpi->iproc[i],ip[i]);
    if (is)  is[i] = ip[i]*imax_local;
    if (ie)  ie[i] = ip[i]*imax_local + isize;
  }
  return(0);
}