VecScatter(const DAD* src, const DAD* dst, const int len,
const DAD* subs [], const int* subsDat [])
The source array is described by the DAD *src and the
destination array is described by the DAD *dst.
len specifies the size of each array element, in bytes.
The source and destination arrays have the same rank, R.
The vectors subs and subsDat have extent R.
If subs [r] is non-null,
the pair *subs [r], subsDat [r] defines
the rth subscript array.
Note well that the source and destination arguments of VecScatter members are reversed relative to the conventions for other communication schedules. This is to emphasize the symmetry with VecGather.