MPI_Gatherv(3)

NAME
     MPI_Gatherv - Gathers values into specified locations from all processes
     in a group

SYNOPSIS
     C:

          #include <mpi.h>

          int MPI_Gatherv ( sendbuf, sendcount,  sendtype, recvbuf,
          recvcounts, displs, recvtype, root, comm )
          void             *sendbuf;
          int               sendcount;
          MPI_Datatype      sendtype;
          void             *recvbuf;
          int              *recvcounts;
          int              *displs;
          MPI_Datatype      recvtype;
          int               root;
          MPI_Comm          comm;


     C++:

          #include <mpi.h>

          void Intracomm::Gatherv(
          const void*       sendbuf,
          int               sendcount,
          const Datatype&   sendtype,
          void*             recvbuf,
          const int         recvcounts[],
          const int         displs[],
          const Datatype&   recvtype,
          int               root) const


     Fortran:

          INCLUDE "mpif.h" (or USE MPI)

          <type> SENDBUF(*), RECVBUF(*)
          INTEGER sendcount, sendtype, recvcounts(*), displs(*),
          recvtype, root, comm, ierror

          CALL MPI_GATHERV(sendbuf, sendcount, sendtype,
          recvbuf, recvcounts(*), displs(*), recvtype, root, comm, ierror)
STANDARDS
     This release implements the MPI 1.2 standard, as documented by the MPI
     Forum in the spring 1997 release of MPI:  A Message Passing Interface
     Standard.

     The MPI_IN_PLACE option as defined in the MPI 2.0 standard is also
     supported in this implementation.

DESCRIPTION
     The MPI_Gatherv routine gathers values into specified locations from all
     processes in a group.  This routine accepts the following parameters:

     sendbuf        Specifies the starting address of the send buffer
                    (choice).  You may also pass in the argument MPI_IN_PLACE
                    for the value of sendbuf at the root.  In such a case,
                    sendcount and sendtype are ignored, and the contribution
                    of the root to the gathered vector is assumed to already
                    be in the correct place in the receive buffer.

     sendcount      Specifies the number of elements in the send buffer
                    (integer).

     sendtype       Specifies the data type of send buffer elements (handle).

     recvcounts     Specifies an integer array (of length group size,
                    specified in comm) containing the number of elements that
                    are received from each process (significant only at root).

     displs         Specifies an integer array (of length group size,
                    specified in comm). Entry i specifies the displacement
                    relative to recvbuf at which to place the incoming data
                    from process i (significant only at root).

     recvtype       Specifies the data type of the receive buffer elements
                    (handle; significant only at root).

     root           Specifies the rank of the receiving process (integer).

     comm           Specifies the communicator (handle).

     recvbuf        Returns the address of the receive buffer (choice;
                    significant only at root).

     ierror         Specifies the return code value for successful completion,
                    which is in MPI_SUCCESS.  MPI_SUCCESS is defined in the
                    mpif.h file.