MPI_Gather(3)

NAME
     MPI_Gather - Gathers values from a group of processes

SYNOPSIS
     C:

          #include <mpi.h>

          int MPI_Gather ( sendbuf, sendcount, sendtype, recvbuf,
          recvcount, recvtype, root, comm )
          void             *sendbuf;
          int               sendcount;
          MPI_Datatype      sendtype;
          void             *recvbuf;
          int               recvcount;
          MPI_Datatype      recvtype;
          int               root;
          MPI_Comm          comm;


     C++:

          #include <mpi.h>

          void Intracomm::Gather(
          const void*       sendbuf,
          int               sendcount,
          const Datatype&   sendtype,
          void*             recvbuf,
          int               recvcount,
          const Datatype&   recvtype,
          int               root) const


     Fortran:

          INCLUDE "mpif.h" (or USE MPI)

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

          CALL MPI_GATHER(sendbuf, sendcount, sendtype,
          recvbuf, recvcount, 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_Gather routine gathers values from a group of processes.  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 the send buffer elements
                    (handle)

     recvcount      Specifies the number of elements for any single receive
                    operation (integer; 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.