MPI_Iscatter function

Article
09/14/2018

Scatters data from one member across all members of a group in a non-blocking way. This function performs the inverse of the operation that is performed by the MPI_Igatherfunction.

Syntax

int MPIAPI MPI_Iscatter(
  _In_opt_  const void         *sendbuf,
  _In_             int         sendcount,
  _In_            MPI_Datatype sendtype,
  _Out_opt_       void         *recvbuf,
  _In_            int          recvcount,
  _In_            MPI_Datatype recvtype,
  _In_            int          root,
  _In_            MPI_Comm     comm,
  _Out_           MPI_Request  *request
);

Parameters

sendbuf [in, optional]
The pointer to a buffer that contains the data to be sent to the root process.

This parameter is ignored for all non-root processes.

If the comm parameter references an intracommunicator, you can specify an in-place option by specifying MPI_IN_PLACE in the root process. The recvcount and recvtype parameters are ignored. The scattered vector is still considered to contain n segments, where n is the group size; the segment that corresponds to the root process is not moved.
sendcount [in]
The number of elements in the send buffer. If sendcount is zero, the data part of the message is empty.

This parameter is ignored for all non-root processes.
sendtype [in]
The data type of each element in the buffer.

This parameter is ignored for all non-root processes.
recvbuf [out, optional]
The handle to a buffer that contains the data that is received on each process. The number and data type of the elements in the buffer are specified in the recvcount and recvtype parameters.
recvcount [in]
The number of elements in the receive buffer. If the count is zero, the data part of the message is empty.
recvtype [in]
The MPI data type of the elements in the receive buffer.
root [in]
The rank of the receiving process within the specified communicator.
comm [in]
The MPI_Comm communicator handle.
request [out]
The MPI_Request handle representing the communication operation.

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_ISCATTER(SENDBUF, SENDCOUNT, SENDTYPE, RECVBUF, RECVCOUNT, RECVTYPE, ROOT, COMM, REQUEST, IERROR)
        <type> SENDBUF(*), RECVBUF(*)
        INTEGER SENDCOUNT, SENDTYPE, RECVCOUNT, RECVTYPE, ROOT, COMM, REQUEST, IERROR

Remarks

A non-blocking call initiates a collective reduction operation which must be completed in a separate completion call. Once initiated, the operation may progress independently of any computation or other communication at participating processes. In this manner, non-blocking reduction operations can mitigate possible synchronizing eﬀects of reduction operations by running them in the “background.”

All completion calls (e.g., MPI_Wait) are supported for non-blocking reduction operations.

Requirements

Product	Microsoft MPI v7
Header	Mpi.h; Mpif.h
Library	Msmpi.lib
DLL	Msmpi.dll