MPI_Group_range_incl function

A group constructor that is used to define a new group by adding additional sets of ranks to an existing group.

Syntax

int MPIAPI MPI_Group_range_incl(
        MPI_Group         group,
        int               n,
        _In_count_(n) int ranges[][3],
  _Out_ MPI_Group         *newgroup
);

Parameters

• group
  The existing group.

• n
  The number of triplets in array ranges.

• ranges
  An array of specifications of processes to include in the new group. Each element of the array specifies a range of process in the form of three integers for the first rank, last rank, and stride.

• newgroup [out]
  A pointer to a handle that represents the new group. The new group contains the additional sets of ranks. The order is defined by ranges.

Return value

Returns MPI_SUCCESS on success. Otherwise, the return value is an error code.

In Fortran, the return value is stored in the IERROR parameter.

Fortran

    MPI_GROUP_RANGE_INCL(GROUP, N, RANGES, NEWGROUP, IERROR)
        INTEGER GROUP, N, RANGES(3,*), NEWGROUP, IERROR

Remarks

If ranges consist of the triplets (first1 , last1, stride1) , ..., (firstn, lastn, striden), then newgroup consists of the sequence of processes in group with ranks first1, first1 + stride1, ..., RoundDown((last1 - first1)/stride1)*stride1, ..., firstn, firstn + striden, ..., RoundDown((lastn - firstn)/striden)*striden.

Each computed rank must be a valid rank in the new group, and all computed ranks must be distinct. Otherwise, the function returns an error.

This is a local operation. Different processes can define distinct groups. A process can define a group that does not include itself.

The MPI implementation does not provide a mechanism to build a group from scratch, but only from existing groups. The base group, upon which all other groups are defined, can be retrieved by using the MPI_Comm_group function. It is the group that is associated with the initial communicator MPI_COMM_WORLD.

Requirements

See also

MPI Group Functions

MPI_Group_incl

MPI_Comm_group