NAME

       MPI_File_set_view - Changes process's view of data in file (collective).

SYNTAX

       C Syntax
           #include <mpi.h>
           int MPI_File_set_view(MPI_File fh, MPI_Offset disp,
                  MPI_Datatype etype, MPI_Datatype filetype,
                  const char *datarep, MPI_Info info)

Fortran Syntax (see FORTRAN 77 NOTES)

           INCLUDE 'mpif.h'
           MPI_FILE_SET_VIEW(FH, DISP, ETYPE,
                   FILETYPE, DATAREP, INFO, IERROR)
             INTEGER FH, ETYPE, FILETYPE, INFO, IERROR
             CHARACTER*(*) DATAREP
             INTEGER(KIND=MPI_OFFSET_KIND) DISP

C++ Syntax

       #include <mpi.h>
       void MPI::File::Set_view(MPI::Offset disp,
            const MPI::Datatype& etype,
            const MPI::Datatype& filetype, const char* datarep,
            const MPI::Info& info)

INPUT/OUTPUT PARAMETER

       fh        File handle (handle).

INPUT PARAMETERS

       disp      Displacement (integer).

       etype     Elementary data type (handle).

       filetype  File type (handle). See Restrictions, below.

       datarep   Data representation (string).

       info      Info object (handle).

OUTPUT PARAMETER

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       The  MPI_File_set_view  routine  changes the process's view of the data in the file -- the
       beginning of the data accessible in the file through that view is set to disp; the type of
       data  is  set  to etype; and the distribution of data to processes is set to filetype.  In
       addition, MPI_File_set_view resets the independent  file  pointers  and  the  shared  file
       pointer to zero. MPI_File_set_view is collective across the fh; all processes in the group
       must pass identical values for datarep and provide an etype with an identical extent.  The
       values  for  disp,  filetype,  and  info  may vary. It is erroneous to use the shared file
       pointer data-access routines unless identical values for disp and filetype are also given.
       The data types passed in etype and filetype must be committed.

       The  disp  displacement argument specifies the position (absolute offset in bytes from the
       beginning of the file) where the view begins.

       The MPI_File_set_view interface allows the user to pass a  data-representation  string  to
       MPI  I/O  via  the datarep argument. To obtain the default value (or "native"), pass NULL.
       The user can also pass information via the info argument. See the HINTS section for a list
       of hints that can be set. For more information, see the MPI-2 standard.

HINTS

       The following hints can be used as values for the info argument.

       SETTABLE HINTS:

       - MPI_INFO_NULL

       -  shared_file_timeout:  Amount of time (in seconds) to wait for access to the shared file
       pointer before exiting with MPI_ERR_TIMEDOUT.

       - rwlock_timeout: Amount of time (in seconds) to wait for obtaining a read or  write  lock
       on a contiguous chunk of a UNIX file before exiting with MPI_ERR_TIMEDOUT.

       -  noncoll_read_bufsize:   Maximum  size  of  the  buffer  used by MPI I/O to satisfy read
       requests in the noncollective data-access routines. (See NOTE, below.)

       - noncoll_write_bufsize: Maximum size of the buffer used  by  MPI  I/O  to  satisfy  write
       requests in the noncollective data-access routines. (See NOTE, below.)

       -  coll_read_bufsize:  Maximum size of the buffer used by MPI I/O to satisfy read requests
       in the collective data-access routines. (See NOTE, below.)

       - coll_write_bufsize:  Maximum size of the  buffer  used  by  MPI  I/O  to  satisfy  write
       requests in the collective data-access routines. (See NOTE, below.)

       NOTE:  A buffer size smaller than the distance (in bytes) in a UNIX file between the first
       byte and the last byte of the access  request  causes  MPI  I/O  to  iterate  and  perform
       multiple  UNIX  read()  or  write()  calls. If the request includes multiple noncontiguous
       chunks of data, and the buffer size is greater than the size of  those  chunks,  then  the
       UNIX  read() or write() (made at the MPI I/O level) will access data not requested by this
       process in order to reduce the total  number  of  write()  calls  made.  If  this  is  not
       desirable behavior, you should reduce this buffer size to equal the size of the contiguous
       chunks within the aggregate request.

       - mpiio_concurrency: (boolean) controls whether nonblocking I/O routines can bind an extra
       thread to an LWP.

       -  mpiio_coll_contiguous:  (boolean)  controls whether subsequent collective data accesses
       will request collectively contiguous regions of the file.

       NON-SETTABLE HINTS:

       - filename: Access this hint to get the name of the file.

FORTRAN 77 NOTES

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

            INTEGER*MPI_OFFSET_KIND DISP

       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.