=+, the difference equation:

xn+2 − 2I1xn+1 + I2xn = 0 (P7.3.a)

allows us to compute the numerical response.

In order to assess the accuracy of the integration method, the local truncation error e(ωh)

can be computed by plugging the exact solution into the difference equation:

xn+2, exact − 2I1xn+1, exact + I2xn, exact = e(ωh) (P7.3.b)