FIG. 7.

Dynamical trajectories for constant C. (a) With no chemotherapy (C = 0), the sensitive corner S is a globally attracting fixed point. All initial conditions inside the triangle move to S along the sample trajectories shown. (b) Above the chemotherapy threshold C > 0.5, all initial conditions inside the triangle move to the resistant corner R. Shown are sample trajectories for C = 0.7. (c) Overlay of the solution trajectories for C = 0 and C = 0.7 create a curvilinear grid throughout the triangle. By switching between these two values of C, we construct a global trajectory made up of segments of the two families of trajectories.