F2 => (sqrt(3.0) - 1.0) / 2.0,
    F3 => (sqrt(4.0) - 1.0) / 3.0,
    F4 => (sqrt(5.0) - 1.0) / 4.0,
    G2 => (3.0 - sqrt(3.0)) / 6.0,  #/3*2
    G3 => (4.0 - sqrt(4.0)) / 12.0, #/4*3   #1.0 / 6.0,
    G4 => (5.0 - sqrt(5.0)) / 20.0, #/5*4