Convergence properties of the four methods GR⁺, GR⁻, OGRM(g = 1), and OGRM(g = |B_n|^-1), in the reference case FFF1⁽⁰⁾. The convergence rate is fast and the norm of the solution reaches its asymptotical value in about 15 iterations, apart from the case of OGRM(g = 1), which converges at a slightly lower rate requiring about 30 iterations.