Figure 16

Figure 16: Difference between the exact and numerical solutions of the following test problem. 2 d-u-+ 4u = S dx2, with S (x < 0 ) = 1 and S (x > 0) = 0. The boundary conditions are u (x = − 1) = 0 and u (x = 1) = 0. The black curve and circles denote results from the multidomain tau method, the red curve and squares from the method based on the homogeneous solutions, the blue curve and diamonds from the variational one, and the green curve and triangles from the collocation method.