The Vector type constructor assumes that the stride between successive blocks is a multiple of the oldtype extent. This avoids, most of the time, the need for computing stride in bytes. Sometimes it is useful to relax this assumption and allow a stride which consists of an arbitrary number of bytes. The Hvector type constructor below achieves this purpose. The usage of both Vector and Hvector is illustrated in Examples -.
MPI_TYPE_HVECTOR(count, blocklength, stride, oldtype, newtype) IN count number of blocks IN blocklength number of elements in each block IN stride spacing between start of each block, measured as number of elements IN oldtype old datatype OUT newtype new datatype
MPI_Type_hvector(int count, int blocklength, MPI_Aint stride, MPI_Datatype oldtype, MPI_Datatype *newtype)
MPI_TYPE_HVECTOR(COUNT, BLOCKLENGTH, STRIDE, OLDTYPE, NEWTYPE, IERROR)INTEGER COUNT, BLOCKLENGTH, STRIDE, OLDTYPE, NEWTYPE, IERROR
MPI_TYPE_HVECTOR is identical to MPI_TYPE_VECTOR, except that stride is given in bytes, rather than in elements. (H stands for ``heterogeneous''). The action of the Hvector constructor is represented schematically in Figure .
Figure: Memory layout of 2D array section for Example . The shaded blocks are sent.