use r_e for zoom in/out - try, p = pi, q = 1; p = 2, q = 1; p = 3, q = 1; p = 4, q = 1; p = 4, q = 0.5; p = 4, q = 0.25; p = 4, q = 0.26; p = 1, q = 0.26; p = 3, q = 4; p = 4, q = 5; p = 3, q = 1.01; p = 10, q = 1.1