NAME

       MPI_File_iwrite_at  -  Writes  a  file  at  an  explicitly  specified offset (nonblocking,
       noncollective).

SYNTAX

C Syntax

       #include <mpi.h> int MPI_File_iwrite_at(MPI_File fh, MPI_Offset  offset,       const  void
       *buf, int count, MPI_Datatype datatype, MPI_Request *request)

Fortran Syntax (see FORTRAN 77 NOTES)

       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_FILE_IWRITE_AT(FH, OFFSET, BUF, COUNT, DATATYPE, REQUEST, IERROR)
            <type>    BUF(*)
            INTEGER   FH, COUNT, DATATYPE, REQUEST, IERROR
            INTEGER(KIND=MPI_OFFSET_KIND) OFFSET

C++ Syntax

       #include <mpi.h>
       MPI::Request MPI::File::Iwrite_at(MPI::Offset offset, const void* buf,
            int count, const MPI::Datatype& datatype)

INPUT/OUTPUT PARAMETER

       fh        File handle (handle).

INPUT PARAMETERS

       offset    File offset (integer).

       buf       Initial address of buffer (choice).

       count     Number of elements in buffer (integer).

       datatype  Data type of each buffer element (handle).

OUTPUT PARAMETERS

       request   Request object (handle).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       MPI_File_iwrite_at  is  a  nonblocking  version of MPI_File_write_at. It attempts to write
       into the file associated with fh (at the offset position) a total  number  of  count  data
       items  having  datatype  type  from  the  user's buffer buf.  The offset is in etype units
       relative to the current view. That is, holes are not counted when locating an offset.  The
       data   is   written  into  those  parts  of  the  file  specified  by  the  current  view.
       MPI_File_iwrite_at stores the number of datatype elements actually written in status.  All
       other  fields  of status are undefined. The request structure can be passed to MPI_Wait or
       MPI_Test, which will return a status with the number of bytes actually accessed.

       It is erroneous to call this function if MPI_MODE_SEQUENTIAL mode was specified  when  the
       file was open.

FORTRAN 77 NOTES

       The  MPI  standard  prescribes  portable  Fortran  syntax for the OFFSET argument only for
       Fortran 90.  FORTRAN 77 users may use the non-portable syntax

            INTEGER*MPI_OFFSET_KIND OFFSET

       where MPI_OFFSET_KIND is a constant defined in mpif.h and gives the length of the declared
       integer in bytes.

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. For  MPI  I/O
       function  errors, the default error handler is set to MPI_ERRORS_RETURN. The error handler
       may   be   changed   with   MPI_File_set_errhandler;   the   predefined   error    handler
       MPI_ERRORS_ARE_FATAL  may  be  used  to  make  I/O  errors  fatal.  Note that MPI does not
       guarantee that an MPI program can continue past an error.