Figure 3: Convergence for of (6) using (8) and the program demo1b.m (a loop of demo1.m) with lambda = 0.999, theta = pi/2, npan = 10, and evec = 1. The reference value is . There are unknowns in the main linear system. (a) Convergence with . (b) The number of iterations needed to meet an estimated relative residual of .