Computational Physics, Physics, Math, Python.
the forward difference formula reveals that it is obtained by subtracting the current step uᵢ,ⱼ from the next step uᵢ₊₁,ⱼ. Intuitively, we can also consider the concept of backward difference. The backward difference can be found by subtracting current step uᵢ,ⱼ with the previous step uᵢ-1,ⱼ