Similar to the numerical schemes for the heat equation, we can use approximation of derivatives by
dierence quotients to arrive at a numerical scheme for the wave equation utt = c2uxx. Since both time and space derivatives are of second order, we use centered dierences to approximate them. Taking a mesh of size t in the t variable, and a mesh of size x in the x variable, we have at the grid points (xj ; tn) = (jx; nt),