Convergence rate of multigrid cycles as function of the number of cycles (or iterations). Blue, orange and purple lines refer to V, F and W cycles respectively, while in green, red and grey we use SOR with relaxation parameter ω = 1.25. In solid, dashed and dotted lines we show results at z = 0,1 and 3 respectively. For the first guess we use one Jacobi step, thereby neglecting the information from previous step.