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MPI_File_iwrite_at(3OpenMPI)                      MPI_File_iwrite_at(3OpenMPI)




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,
                  void *buf, int count, MPI_Datatype datatype, MPI_Request *request)

       Fortran Syntax (see FORTRAN 77 NOTES)
           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 posi-
       tion) 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 cur-
       rent 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  actu-
       ally  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_SEQENTIAL 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-porta-
       ble 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++  func-
       tions  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.




Open MPI 1.2                    September 2006    MPI_File_iwrite_at(3OpenMPI)

Mac OS X 10.6 - Generated Thu Sep 17 20:13:00 CDT 2009
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