NAME

       MPI_Type_vector - Creates a vector (strided) datatype.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Type_vector(int count, int blocklength, int stride,
            MPI_Datatype oldtype, MPI_Datatype *newtype)

Fortran Syntax

       INCLUDE 'mpif.h'
       MPI_TYPE_VECTOR(COUNT, BLOCKLENGTH, STRIDE, OLDTYPE, NEWTYPE,
                 IERROR)
            INTEGER   COUNT, BLOCKLENGTH, STRIDE, OLDTYPE
            INTEGER   NEWTYPE, IERROR

C++ Syntax

       #include <mpi.h>
       Datatype Datatype::Create_vector(int count, int blocklength,
            int stride) const

INPUT PARAMETERS

       count     Number of blocks (nonnegative integer).

       blocklength
                 Number of elements in each block (nonnegative integer).

       stride    Number of elements between start of each block (integer).

       oldtype   Old datatype (handle).

OUTPUT PARAMETERS

       newtype   New datatype (handle).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       The  function  MPI_Type_vector  is  a  general  constructor  that  allows replication of a
       datatype into locations that consist of equally spaced blocks. Each block is  obtained  by
       concatenating the same number of copies of the old datatype. The spacing between blocks is
       a multiple of the extent of the old datatype.

       Example 1: Assume, again, that oldtype has type map {(double, 0), (char, 8)}, with  extent
       16.  A  call  to  MPI_Type_vector(2, 3, 4, oldtype, newtype) will create the datatype with
       type map
           {(double, 0), (char, 8), (double, 16), (char, 24),
           (double, 32), (char, 40),
           (double, 64), (char, 72),
           (double, 80), (char, 88), (double, 96), (char, 104)}

       That is, two blocks with three copies each of the old type, with a stride of 4 elements (4
       x 6 bytes) between the blocks.

       Example  2:   A  call  to   MPI_Type_vector(3,  1,  -2,  oldtype, newtype) will create the
       datatype

           {(double, 0), (char, 8), (double, -32), (char, -24),
           (double, -64), (char, -56)}

       In general, assume that oldtype has type map

           {(type(0), disp(0)), ..., (type(n-1), disp(n-1))},

       with extent ex. Let bl be the blocklength. The newly created datatype has a type map  with
       count x bl x  n entries:

           {(type(0), disp(0)), ..., (type(n-1), disp(n-1)),
           (type(0), disp(0) + ex), ..., (type(n-1), disp(n-1) + ex), ...,
           (type(0), disp(0) + (bl -1) * ex),...,
           (type(n-1), disp(n-1) + (bl -1)* ex),
           (type(0), disp(0) + stride * ex),..., (type(n-1),
           disp(n-1) + stride * ex), ...,
           (type(0), disp(0) + (stride + bl - 1) * ex), ...,
           (type(n-1), disp(n-1) + (stride + bl -1) * ex), ...,
           (type(0), disp(0) + stride * (count -1) * ex), ...,
           (type(n-1), disp(n-1) + stride * (count -1) * ex), ...,
           (type(0), disp(0) + (stride * (count -1) + bl -1) * ex), ...,
           (type(n-1), disp(n-1) + (stride * (count -1) + bl -1) * ex)}

       A  call  to  MPI_Type_contiguous(count,  oldtype,  newtype)  is  equivalent  to  a call to
       MPI_Type_vector(count, 1, 1, oldtype, newtype), or to a call to MPI_Type_vector(1,  count,
       n, oldtype, newtype), n arbitrary.

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.

SEE ALSO

       MPI_Type_create_hvector
       MPI_Type_hvector