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NAME

       MPI_Type_create_darray - Creates a distributed array datatype;

SYNTAX


C Syntax

       #include <mpi.h>
       int MPI_Type_create_darray(int size, int rank, int ndims,
            int array_of_gsizes[], int array_of_distribs[],
            int array_of_dargs[], int array_of_psizes[],
            int order, MPI_Datatype oldtype, MPI_Datatype *newtype)

Fortran Syntax

       INCLUDE 'mpif.h'
       MPI_TYPE_CREATE_DARRAY(SIZE, RANK, NDIMS, ARRAY_OF_GSIZES,
            ARRAY_OF_DISTRIBS, ARRAY_OF_DARGS, ARRAY_OF_PSIZES, ORDER,
            OLDTYPE, NEWTYPE, IERROR)

            INTEGER   SIZE, RANK, NDIMS, ARRAY_OF_GSIZES(*), ARRAY_OF_DISTRIBS(*),
                 ARRAY_OF_DARGS(*), ARRAY_OF_PSIZES(*), ORDER, OLDTYPE,
                 NEWTYPE, IERROR

C++ Syntax

       #include <mpi.h>
       MPI::Datatype MPI::Datatype::Create_darray(int size, int rank,
            int ndims, const int array_of_gsizes[],
            const int array_of_distribs[], const int array_of_dargs[],
            const int array_of_psizes[], int order) const

INPUT PARAMETERS

       size      Size of process group (positive integer).

       rank      Rank in process group (nonnegative integer).

       ndims     Number of array dimensions as well as process grid dimensions
                 (positive integer).

       array_of_gsizes
                 Number of elements of  type  oldtype  in  each  dimension  of
                 global array (array of positive integers).

       array_of_distribs
                 Distribution of array in each dimension (array of state).

       array_of_dargs
                 Distribution  argument  in  each dimension (array of positive
                 integers).

       array_of_psizes
                 Size of process grid in each  dimension  (array  of  positive
                 integers).

       order     Array storage order flag (state).

       oldtype   Old data type (handle).

OUTPUT PARAMETERS

       newtype   New data type (handle).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       MPI_Type_create_darray   can   be  used  to  generate  the  data  types
       corresponding to the distribution  of  an  ndims-dimensional  array  of
       oldtype  elements  onto an ndims-dimensional grid of logical processes.
       Unused dimensions of array_of_psizes should be set to 1. For a call  to
       MPI_Type_create_darray to be correct, the equation

           ndims-1
         pi              array_of_psizes[i] = size
           i=0

       must  be  satisfied.  The  ordering of processes in the process grid is
       assumed to be row-major, as in the case of  virtual  Cartesian  process
       topologies in MPI-1.

       Each dimension of the array can be distributed in one of three ways:

       - MPI_DISTRIBUTE_BLOCK - Block distribution
       - MPI_DISTRIBUTE_CYCLIC - Cyclic distribution
       - MPI_DISTRIBUTE_NONE - Dimension not distributed.

       The  constant MPI_DISTRIBUTE_DFLT_DARG specifies a default distribution
       argument. The  distribution  argument  for  a  dimension  that  is  not
       distributed  is  ignored. For any dimension i in which the distribution
       is MPI_DISTRIBUTE_BLOCK, it erroneous to  specify  array_of_dargs[i]  *
       array_of_psizes[i] < array_of_gsizes[i].

       For   example,   the   HPF   layout  ARRAY(CYCLIC(15))  corresponds  to
       MPI_DISTRIBUTE_CYCLIC with a distribution argument of 15, and  the  HPF
       layout   ARRAY(BLOCK)   corresponds   to  MPI_DISTRIBUTE_BLOCK  with  a
       distribution argument of MPI_DISTRIBUTE_DFLT_DARG.

       The order argument is used as in  MPI_TYPE_CREATE_SUBARRAY  to  specify
       the storage order. Therefore, arrays described by this type constructor
       may be stored in Fortran (column-major) or C (row-major)  order.  Valid
       values for order are MPI_ORDER_FORTRAN and MPI_ORDER_C.

       This  routine  creates  a  new  MPI data type with a typemap defined in
       terms of a function called "cyclic()" (see below).

       Without loss of generality, it suffices to define the typemap  for  the
       MPI_DISTRIBUTE_CYCLIC case where MPI_DISTRIBUTE_DFLT_DARG is not used.

       MPI_DISTRIBUTE_BLOCK  and  MPI_DISTRIBUTE_NONE  can  be  reduced to the
       MPI_DISTRIBUTE_CYCLIC case for dimension i as follows.

       MPI_DISTRIBUTE_BLOCK     with      array_of_dargs[i]      equal      to
       MPI_DISTRIBUTE_DFLT_DARG  is  equivalent  to MPI_DISTRIBUTE_CYCLIC with
       array_of_dargs[i] set to

          (array_of_gsizes[i] + array_of_psizes[i] - 1)/array_of_psizes[i]

       If   array_of_dargs[i]   is    not    MPI_DISTRIBUTE_DFLT_DARG,    then
       MPI_DISTRIBUTE_BLOCK and DISTRIBUTE_CYCLIC are equivalent.

       MPI_DISTRIBUTE_NONE   is   equivalent   to  MPI_DISTRIBUTE_CYCLIC  with
       array_of_dargs[i] set to array_of_gsizes[i].

       Finally,  MPI_DISTRIBUTE_CYCLIC   with   array_of_dargs[i]   equal   to
       MPI_DISTRIBUTE_DFLT_DARG  is  equivalent  to MPI_DISTRIBUTE_CYCLIC with
       array_of_dargs[i] set to 1.

NOTES

       For both Fortran and C arrays, the ordering of processes in the process
       grid  is  assumed to be row-major. This is consistent with the ordering
       used in virtual Cartesian process topologies in MPI-1. To  create  such
       virtual  process topologies, or to find the coordinates of a process in
       the process grid, etc.,  users  may  use  the  corresponding  functions
       provided in MPI-1.

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. By default, this error handler aborts the MPI job,  except  for
       I/O   function   errors.   The   error  handler  may  be  changed  with
       MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN
       may  be  used  to cause error values to be returned. Note that MPI does
       not guarantee that an MPI program can continue past an error.



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