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MPI_Comm_rank - Determines the rank of the calling process in the
communicator.
#include <mpi.h>
int MPI_Comm_rank(MPI_Comm comm, int *rank)
USE MPI
! or the older form: INCLUDE ’mpif.h’
MPI_COMM_RANK(COMM, RANK, IERROR)
INTEGER COMM, RANK, IERROR
USE mpi_f08
MPI_Comm_rank(comm, rank, ierror)
TYPE(MPI_Comm), INTENT(IN) :: comm
INTEGER, INTENT(OUT) :: rank
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
- comm
- Communicator (handle).
- rank
- Rank
of the calling process in group of comm (integer).
- IERROR
- Fortran only:
Error status (integer).
This function gives the rank of the
process in the particular communicator’s group. It is equivalent to accessing
the communicator’s group with MPI_Comm_group, computing the rank using MPI_Group_rank,
and then freeing the temporary group via MPI_Group_free.
Many programs will
be written with the manager-worker model, where one process (such as the
rank-zero process) will play a supervisory role, and the other processes
will serve as compute nodes. In this framework, MPI_Comm_size and MPI_Comm_rank
are useful for determining the roles of the various processes of a communicator.
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.
MPI_Comm_group
MPI_Comm_size
MPI_Comm_compare
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