NAME

       MPI_Comm_compare  -  Compares two communicators.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Comm_compare(MPI_Comm comm1, MPI_Comm comm2, int *result)

Fortran Syntax

       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_COMM_COMPARE(COMM1, COMM2, RESULT, IERROR)
            INTEGER   COMM1, COMM2, RESULT, IERROR

Fortran 2008 Syntax

       USE mpi_f08
       MPI_Comm_compare(comm1, comm2, result, ierror)
            TYPE(MPI_Comm), INTENT(IN) :: comm1, comm2
            INTEGER, INTENT(OUT) :: result
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror

C++ Syntax

       #include <mpi.h>
       static int Comm::Compare(const Comm& comm1, const Comm& comm2)

INPUT PARAMETERS

       comm1     Comm1 (handle).

       comm2     Comm2 (handle).

OUTPUT PARAMETERS

       result    Result of comparison (integer).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       MPI_IDENT  results  if  and  only  if  comm1  and  comm2  are  handles for the same object
       (identical groups and same contexts). MPI_CONGRUENT results if the underlying  groups  are
       identical  in  constituents  and  rank  order; these communicators differ only by context.
       MPI_SIMILAR results of the group members of both communicators are the same but  the  rank
       order differs. MPI_UNEQUAL results otherwise.

ERRORS

       Almost all MPI routines return an error value; C routines as the value of the function and
       Fortran routines in the last argument. C++ functions do not return errors. If the  default
       error  handler  is  set  to  MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception
       mechanism will be used to throw an MPI::Exception object.

       Before the error value is returned, the current MPI error handler is called.  By  default,
       this  error  handler aborts the MPI job, except for I/O function errors. The error handler
       may   be   changed   with   MPI_Comm_set_errhandler;   the   predefined   error    handler
       MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not
       guarantee that an MPI program can continue past an error.