NAME

       MPI_File_read_at_all_begin  - Reads a file at explicitly specified offsets; beginning part
       of a split collective routine (nonblocking).

SYNTAX

C Syntax

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

Fortran Syntax (see FORTRAN 77 NOTES)

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

C++ Syntax

       #include <mpi.h>
       void MPI::File::Read_at_all_begin(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 buffer (integer).

       datatype  Data type of each buffer element.

OUTPUT PARAMETERS

       buf       Initial address of buffer (choice).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       MPI_File_read_at_all_begin  is  the  beginning  part  of  a  split collective 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.

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.

NOTES

       All  the  nonblocking  collective  routines for data access are "split" into two routines,
       each with _begin or _end as a suffix. These split collective routines are subject  to  the
       semantic rules described in Section 9.4.5 of the MPI-2 standard.

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.