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MPI_Comm_create - Creates a new communicator.
#include <mpi.h>
int MPI_Comm_create(MPI_Comm comm, MPI_Group group, MPI_Comm *newcomm)
USE MPI
! or the older form: INCLUDE ’mpif.h’
MPI_COMM_CREATE(COMM, GROUP, NEWCOMM, IERROR)
INTEGER COMM, GROUP, NEWCOMM, IERROR
USE mpi_f08
MPI_Comm_create(comm, group, newcomm, ierror)
TYPE(MPI_Comm), INTENT(IN) :: comm
TYPE(MPI_Group), INTENT(IN) :: group
TYPE(MPI_Comm), INTENT(OUT) :: newcomm
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
- comm
- Communicator (handle).
- group
- Group, which is a subset
of the group of comm (handle).
- newcomm
- New communicator
(handle).
- IERROR
- Fortran only: Error status (integer).
This function
creates a new communicator newcomm with communication group defined by
group and a new context. The function sets newcomm to a new communicator
that spans all the processes that are in the group. It sets newcomm to
MPI_COMM_NULL for processes that are not in the group.
Each process must
call with a group argument that is a subgroup of the group associated with
comm; this could be MPI_GROUP_EMPTY. The processes may specify different
values for the group argument. If a process calls with a non-empty group,
then all processes in that group must call the function with the same group
as argument, that is: the same processes in the same order. Otherwise the
call is erroneous.
MPI_Comm_create provides a means of making a subset
of processes for the purpose of separate MIMD computation, with separate
communication space. newcomm, which is created by MPI_Comm_create, can be
used in subsequent calls to MPI_Comm_create (or other communicator constructors)
to further subdivide a computation into parallel sub-computations. A more
general service is provided by MPI_Comm_split.
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_split
MPI_Intercomm_create MPI_Comm_create_group
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