Numerical dispersion in the frequency domain. Use your code from Problem 5.6 to propagate a Gaussian pulse along the 1D grid. Monitor the pulse as it passes through a point some distance x from the left end; use this pulse to plot the propagation speed as a function of frequency. Compare to the analytical and numerical dispersion relations. Repeat for vp?t/?x = 1, 0.9, 0.7, and 0.5.