NAME

       MPI_Start - Initiates a communication using a persistent request handle.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Start(MPI_Request *request)

Fortran Syntax

       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_START(REQUEST, IERROR)
            INTEGER   REQUEST, IERROR

Fortran 2008 Syntax

       USE mpi_f08
       MPI_Start(request, ierror)
            TYPE(MPI_Request), INTENT(INOUT) :: request
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror

C++ Syntax

       #include <mpi.h>
       void Prequest::Start()

INPUT PARAMETER

       request   Communication request (handle).

OUTPUT PARAMETER

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       A  communication  (send  or  receive)  that  uses a persistent request is initiated by the
       function MPI_Start.

       The argument, request, is a handle returned by one of the persistent communication-request
       initialization  functions (MPI_Send_init, MPI_Bsend_init,  MPI_Ssend_init, MPI_Rsend_init,
       MPI_Recv_init). The associated request should be inactive and becomes active once the call
       is made.

       If  the  request  is  for a send with ready mode, then a matching receive should be posted
       before the call is made. From the  time  the  call  is  made  until  after  the  operation
       completes, the communication buffer should not be accessed.

       The call is local, with semantics similar to the nonblocking communication operations (see
       Section 3.7 in the MPI-1 Standard,  "Nonblocking  Communication.")  That  is,  a  call  to
       MPI_Start  with  a  request  created  by  MPI_Send_init starts a communication in the same
       manner  as  a  call  to  MPI_Isend;  a  call  to  MPI_Start  with  a  request  created  by
       MPI_Bsend_init  starts  a communication in the same manner as a call to MPI_Ibsend; and so
       on.

ERRORS

       Almost all MPI routines return an error value; C routines as the value of the function and
       Fortran  routines in the last argument. C++ functions do not return errors. If the default
       error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then  on  error  the  C++  exception
       mechanism will be used to throw an MPI::Exception object.

       Before  the  error value is returned, the current MPI error handler is called. By default,
       this error handler aborts the MPI job, except for I/O function errors. The  error  handler
       may    be   changed   with   MPI_Comm_set_errhandler;   the   predefined   error   handler
       MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not
       guarantee that an MPI program can continue past an error.

SEE ALSO

       MPI_Bsend_init
       MPI_Rsend_init
       MPI_Send_init
       MPI_Sssend_init
       MPI_Recv_init
       MPI_Startall