Compares two communicators


#include "mpi.h"
int MPI_Comm_compare ( comm1, comm2, result )
MPI_Comm  comm1;
MPI_Comm  comm2;
int       *result;

Input Parameters

comm1 comm1 (handle)
comm2 comm2 (handle)

Output Parameter

integer which is MPI_IDENT if the contexts and groups are the same, MPI_CONGRUENT if different contexts but identical groups, MPI_SIMILAR if different contexts but similar groups, and MPI_UNEQUAL otherwise

Notes for Fortran

All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK) havean additional argument ierr at the end of the argument list. ierris an integer and has the same meaning as the return value of the routinein C. In Fortran, MPI routines are subroutines, and are invoked with thecall statement.

All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGERin Fortran.


All MPI routines (except MPI_Wtime and MPI_Wtick) return an error value; C routines as the value of the function and Fortran routines in the lastargument. Before the value is returned, the current MPI error handler iscalled. By default, this error handler aborts the MPI job. The error handlermay be changed with MPI_Errhandler_set; the predefined error handlerMPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarentee that an MPI program can continue pastan error.

No error; MPI routine completed successfully.
Invalid argument. Some argument is invalid and is not identified by a specific error class (e.g., MPI_ERR_RANK).