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)

       USE MPI
       ! or the older form: 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.