a = CurveCartesian(cos(t), sin(t), t, 0, 6.283185307179586)
b = CurveCartesian(cos(t) + t / 2, sin(t), t, 0, 25.13274)
c = CurveCartesian(t^(2), t^(3), t, -1, 1)
d = CurveCartesian(t * abs(t), t^(2), t, -1, 1)