NAME

       MPI_Alltoallw   -   Generalized  all-to-all  communication  allowing  different  datatypes,  counts,  and
       displacements for each partner

SYNOPSIS

       int MPI_Alltoallw(const void *sendbuf, const int sendcounts[],
                         const int sdispls[], const MPI_Datatype sendtypes[],
                         void *recvbuf, const int recvcounts[], const int rdispls[],
                         const MPI_Datatype recvtypes[], MPI_Comm comm)

INPUT PARAMETERS

       sendbuf
              - starting address of send buffer (choice)
       sendcounts
              - integer array equal to the group size  specifying  the  number  of  elements  to  send  to  each
              processor (integer)
       sdispls
              -  integer  array (of length group size). Entry j specifies the displacement in bytes (relative to
              sendbuf) from which to take the outgoing data destined for process j
       sendtypes
              - array of datatypes (of length group size). Entry j specifies the type of data to send to process
              j (handle)
       recvcounts
              -  integer  array  equal  to the group size specifying the number of elements that can be received
              from each processor (integer)
       rdispls
              - integer array (of length group size). Entry i specifies the displacement in bytes  (relative  to
              recvbuf) at which to place the incoming data from process i
       recvtypes
              -  array  of  datatypes  (of  length group size). Entry i specifies the type of data received from
              process i (handle)
       comm   - communicator (handle)

OUTPUT PARAMETERS

       recvbuf
              - address of receive buffer (choice)

THREAD AND INTERRUPT SAFETY

       This routine is thread-safe.  This means that this routine may be safely used by multiple threads without
       the  need  for  any  user-provided thread locks.  However, the routine is not interrupt safe.  Typically,
       this is due to the use of memory allocation routines such as malloc or other non-MPICH  runtime  routines
       that are themselves not interrupt-safe.

NOTES FOR FORTRAN

       All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have an additional argument ierr at the
       end of the argument list.  ierr is an integer and has the same meaning as the return value of the routine
       in C.  In Fortran, MPI routines are subroutines, and are invoked with the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

ERRORS

       All  MPI routines (except MPI_Wtime and MPI_Wtick ) return an error value; C routines as the value of the
       function and Fortran routines in the last argument.  Before the value is returned, the current MPI  error
       handler  is called.  By default, this error handler aborts the MPI job.  The error handler may be changed
       with   MPI_Comm_set_errhandler   (for   communicators),   MPI_File_set_errhandler   (for   files),    and
       MPI_Win_set_errhandler  (for  RMA windows).  The MPI-1 routine MPI_Errhandler_set may be used but its use
       is deprecated.  The predefined error handler MPI_ERRORS_RETURN may be used to cause error  values  to  be
       returned.   Note that MPI does not guarentee that an MPI program can continue past an error; however, MPI
       implementations will attempt to continue whenever possible.

       MPI_SUCCESS
              - No error; MPI routine completed successfully.
       MPI_ERR_COMM
              - Invalid communicator.  A common error is to use a null communicator in a call (not even  allowed
              in MPI_Comm_rank ).
       MPI_ERR_ARG
              -  Invalid  argument.   Some  argument  is invalid and is not identified by a specific error class
              (e.g., MPI_ERR_RANK ).
       MPI_ERR_COUNT
              - Invalid count argument.  Count arguments must be non-negative; a count of zero is often valid.
       MPI_ERR_TYPE
              - Invalid datatype argument.  May be an uncommitted MPI_Datatype (see MPI_Type_commit ).

LOCATION

       src/mpi/coll/alltoallw.c

                                                    4/24/2013                                   MPI_Alltoallw(3)