Makes a group from the difference of two groups.
#include <mpi.h> int MPI_Group_difference(MPI_Group group1, MPI_Group group2, MPI_Group *newgroup)
INCLUDE 'mpif.h' MPI_GROUP_DIFFERENCE(GROUP1, GROUP2, NEWGROUP, IERROR) INTEGER GROUP1, GROUP2, NEWGROUP, IERROR
#include <mpi.h> static Group Group::Difference(const Group& group1, const Group& group2)
First group (handle).
Second group (handle).
Difference group (handle).
Fortran only: Error status (integer).
The set-like operations are defined as follows:
union -- All elements of the first group (group1), followed by all elements of second group (group2) that are not in the first group
intersect -- all elements of the first group that are also in the second group, ordered as in first group
difference -- all elements of the first group that are not in the second group, ordered as in the first group
Note that for these operations the order of processes in the output group is determined primarily by order in the first group (if possible) and then, if necessary, by order in the second group. Neither union nor intersection are commutative, but both are associative.
The new group can be empty, that is, equal to MPI_GROUP_EMPTY.
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.