function [Linf, L2] = pset3prob3b(dxs, T, lambda)
  for i = 1:length(dxs)
    dx = dxs(i);
    mu = lambda/dx;
    x = [-1:dx:1-dx];
    disp(sprintf('dx = %g, N = %d\n', dx, length(x)));
    u = (abs(x) < 0.5) * 1; u(abs(abs(x) - 0.5) < 1e-8) = 0.5;
    tic;
    u = pset3prob3(x, u, T, 1, mu);
    toc
    u0 = uheat0(x, T, 10);
    Linf(i) = max(abs(u - u0));
    L2(i) = sqrt(sum((u - u0).^2) * dx);
  end