Here are some supplemental notes for Chapter 6.  

Two main programs are provided in listing-6p1-6p3:

pde_1_main.m      Main program in Chapter 6 as discussed with Listing 6.1

pde_1a_main.m     pde_1_main.m with additional coding to calculate the front
                  velocity in Listing 6.3 

pde_1.m           ODE routine in Listing 6.2 (called by both main programs)