NAME

       MPI_File_iread  -  Reads  a file starting at the location specified by the individual file
       pointer (nonblocking, noncollective).

SYNTAX

C Syntax

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

Fortran Syntax

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

C++ Syntax

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

INPUT/OUTPUT PARAMETER

       fh        File handle (handle).

INPUT PARAMETERS

       count     Number of elements in the buffer (integer).

       datatype  Data type of each buffer element (handle).

OUTPUT PARAMETERS

       buf       Initial address of buffer (choice).

       request   Request object (handle).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       MPI_File_iread  is  a  nonblocking  version of MPI_File_read. It attempts to read from the
       file associated with fh at the current individual file pointer position maintained by  the
       system in which a total number of count data items having datatype type  are read into the
       user's buffer buf.  The data is taken out of those parts of  the  file  specified  by  the
       current  view.  MPI_File_iread  stores  the  number of data-type elements actually read in
       status.  All other fields of status are undefined. It is erroneous to call  this  function
       if MPI_MODE_SEQUENTIAL mode was specified when the file was opened.

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.