Get read-only pointer to contiguous array containing this processor’s portion of the vector data.
x - the vector
a - the array
The array must be returned using a matching call to
VecGetArray(), preserves cached information like vector norms.
Standard PETSc vectors use contiguous storage so that this routine does not perform a copy. Other vector implementations may require a copy, but such implementations should cache the contiguous representation so that only one copy is performed when this routine is called multiple times in sequence.