Creates an intracommuncator from an intercommunicator
int MPI_Intercomm_merge ( comm, high, comm_out )
- comm - Intercommunicator
- high - Used to order the groups of the two intracommunicators within comm
when creating the new communicator.
- comm_out - Created intracommunicator
Notes for Fortran
All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK) have
an additional argument ierr at the end of the argument list. ierr
is an integer and has the same meaning as the return value of the routine
in C. In Fortran, MPI routines are subroutines, and are invoked with the
All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGER
1) Allocate two contexts
2) Local and remote group leaders swap high values
3) Determine the high value.
4) Merge the two groups and make the intra-communicator
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 last
argument. Before the value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job. The error handler
may be changed with MPI_Errhandler_set; the predefined error handler
MPI_ERRORS_RETURN may be used to cause error values to be returned.
Note that MPI does not guarentee that an MPI program can continue past
- MPI_SUCCESS - No error; MPI routine completed successfully.
- MPI_ERR_COMM - Invalid communicator. A common error is to use a null
communicator in a call (not even allowed in MPI_Comm_rank).
- MPI_ERR_INTERN - This error is returned when some part of the MPICH
implementation is unable to acquire memory.