MPI_Type_create_darray(3)          Open MPI          MPI_Type_create_darray(3)



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.





1.4.1                            Jan 14, 2010        MPI_Type_create_darray(3)
