MPI_Intercomm_merge
Creates an intracommuncator from an intercommunicator
Synopsis
int MPI_Intercomm_merge(MPI_Comm intercomm, int high, MPI_Comm *newintracomm)
Input Parameters
- comm
- Intercommunicator
- high
- Used to order the groups of the two intracommunicators within comm
when creating the new communicator. This is a boolean value; the group
that sets high true has its processes ordered after the group that sets
this value to false.
Output Parameter
- 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
call statement.
All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGER
in Fortran.
Algorithm
1) Allocate 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
Errors
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
an error.
- 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.
See Also
MPI_Intercomm_create, MPI_Comm_free
MPI_Intercomm_merge - merge communicators
Arguments
- MPI_Comm intercomm
- intercommunicator
- int high
- high
- MPI_Comm *newintracomm
- new intracommunicator
Notes
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
call statement.
All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGER
in Fortran.
Errors
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
an error.
- MPI_SUCCESS
- No error; MPI routine completed successfully.
Location:intercomm_merge.c