1. Alternation over a group of subscripts is defined in a similar manner

2. Similarly, we can find Approximations of different order, using different points, for the different derivatives.! The next two slides list several such Approximations (using subscripts to denote the different grid points)! Finite Difference Approximations! Computational Fluid Dynamics!!f!x = f j+1" h +O(h)!f!x = f j" "1 h +O(h)!f!x = f j+ 1