focal (3) MPI_Type_create_hindexed_block.openmpi.3.gz

NAME

       MPI_Type_create_indexed_block -  Create an indexed datatype with constant-sized blocks

SYNOPSIS

       int MPI_Type_create_indexed_block(int count,
       int blocklength,
       const int array_of_displacements[],
       MPI_Datatype oldtype, MPI_Datatype * newtype)

INPUT PARAMETERS

       count  - length of array of displacements (integer)
       blocklength
              - size of block (integer)
       array_of_displacements
              - array of displacements (array of integer)
       oldtype
              - old datatype (handle)

OUTPUT PARAMETERS

       newtype
              - new datatype (handle)

NOTES

       The  indices  are  displacements, and are based on a zero origin.  A common error is to do something like
       the following
       integer a(100)
       integer blens(10), indices(10)
       do i=1,10
       10       indices(i) = 1 + (i-1)*10
       call MPI_TYPE_CREATE_INDEXED_BLOCK(10,1,indices,MPI_INTEGER,newtype,ierr)
       call MPI_TYPE_COMMIT(newtype,ierr)
       call MPI_SEND(a,1,newtype,...)

       expecting this to send "a(1),a(11),..." because the indices have values "1,11,...".   Because  these  are
       displacements from the beginning of "a", it actually sends "a(1+1),a(1+11),...".

       If you wish to consider the displacements as indices into a Fortran array, consider declaring the Fortran
       array with a zero origin
       integer a(0:99)

THREAD AND INTERRUPT SAFETY

       This routine is thread-safe.  This means that this routine may be safely used by multiple threads without
       the  need  for  any  user-provided thread locks.  However, the routine is not interrupt safe.  Typically,
       this is due to the use of memory allocation routines such as malloc or other non-MPICH  runtime  routines
       that are themselves not interrupt-safe.

NOTES FOR FORTRAN

       All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have an additional argument ierr at the
       end of the argument list.  ierr is an integer and has the same meaning as the return value of the routine
       in C.  In Fortran, MPI routines are subroutines, and are invoked with the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

ERRORS

       All  MPI routines (except MPI_Wtime and MPI_Wtick ) return an error value; C routines as the value of the
       function and Fortran routines in the last argument.  Before the value is returned, the current MPI  error
       handler  is called.  By default, this error handler aborts the MPI job.  The error handler may be changed
       with   MPI_Comm_set_errhandler   (for   communicators),   MPI_File_set_errhandler   (for   files),    and
       MPI_Win_set_errhandler  (for  RMA windows).  The MPI-1 routine MPI_Errhandler_set may be used but its use
       is deprecated.  The predefined error handler MPI_ERRORS_RETURN may be used to cause error  values  to  be
       returned.   Note that MPI does not guarentee that an MPI program can continue past an error; however, MPI
       implementations will attempt to continue whenever possible.

       MPI_SUCCESS
              - No error; MPI routine completed successfully.
       MPI_ERR_TYPE
              - Invalid datatype argument.  Additionally, this error can occur if  an  uncommitted  MPI_Datatype
              (see MPI_Type_commit ) is used in a communication call.
       MPI_ERR_ARG
              -  Invalid  argument.   Some  argument  is invalid and is not identified by a specific error class
              (e.g., MPI_ERR_RANK ).

                                                   11/12/2019                   MPI_Type_create_indexed_block(3)