Element Level Approach
Key difference from ëstandardí PCG is in the statement:
u = MATMUL(A,p)
- where A is a (sparse) matrix and p a (long) vector (number of equations)
In the element level approach, this is replaced by:
u(g) = u(g) + utemp
- data is gathered from the p vector; then used in a dense matrix-vector multiplication; then scattered into the u vector