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MPI_File_iread_at(3OpenMPI)                        MPI_File_iread_at(3OpenMPI)




NAME

       MPI_File_iread_at  -  Reads  a  file  at an explicitly specified offset
       (nonblocking, noncollective).



SYNTAX

       C Syntax
           #include <mpi.h>
           int MPI_File_iread_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_IREAD_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::Iread_at(MPI::Offset offset, void* buf,
            int count, const MPI::Datatype& datatype)



INPUT PARAMETERS

       fh        File handle (handle).

       offset    File offset (integer).

       count     Number of elements in the buffer (integer).

       datatype  Data type of each buffer element (handle).



OUTPUT PARAMETERS

       buf       Initial address of the buffer (choice).

       request   Request object (handle).

       IERROR    Fortran only: Error status (integer).



DESCRIPTION

       MPI_File_iread_at is the nonblocking version of MPI_File_read_at.

       MPI_File_iread_at is a nonblocking routine that attempts to  read  from
       the  file  associated  with fh at the offset position a total number of
       count data items having datatype type into 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 taken out of those
       parts  of  the  file  specified  by the current view. MPI_File_iread_at
       stores the number of datatype elements actually read  in  status.   All
       other fields of status are undefined.



FORTRAN 77 NOTES

       The  MPI  standard  prescribes  portable  Fortran syntax for the OFFSET
       argument only for Fortran 90.  Sun 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++ 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_iread_at(3OpenMPI)

Mac OS X 10.6 - Generated Thu Sep 17 20:12:59 CDT 2009
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