MPI_Group_size − Returns the size of a group.
#include
<mpi.h>
int MPI_Group_size(MPI_Group group, int
*size)
USE MPI
! or the older form: INCLUDE ’mpif.h’
MPI_GROUP_SIZE(GROUP, SIZE, IERROR)
INTEGER |
GROUP, SIZE, IERROR |
USE mpi_f08
MPI_Group_size(group, size, ierror)
TYPE(MPI_Group), INTENT(IN) :: group | |
INTEGER, INTENT(OUT) :: size | |
INTEGER, OPTIONAL, INTENT(OUT) :: ierror |
group |
Group (handle). |
size |
Number of processes in the group (integer). |
|||
IERROR |
Fortran only: Error status (integer). |
MPI_Group_size returns in size the number of processes in the group. Thus, if group = MPI_GROUP_EMPTY, then the call will return size = 0. On the other hand, a call with group = MPI_GROUP_NULL is erroneous.
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.