a = 0.1 (slider from -1 to 1, step 0.1)
b = 0.1 (slider from -1 to 1, step 0.1)
b_s = CurveCartesian(t, b, t, -1, 1)
a_s = CurveCartesian(a, t, t, -1, 1)
B = Point(b_s)
A = Point(a_s)
l1 = Sequence(CurveCartesian[a, t, t, -1, 1], a, -1, 1, 0.1)
l2 = Sequence(CurveCartesian[t, b, t, -1, 1], b, -1, 1, 0.1)
c: carctan(-3, 4)
d: (c / π * 180)
l3 = Sequence(CurveCartesian[log(sqrt(a^(2) + t^(2))), carctan(a, t), t, -1, 1], a, -1, 1, 0.1)
bia = CurveCartesian(log(sqrt(a^(2) + t^(2))), carctan(a, t), t, -1, 1)
A': (log(sqrt(x(A)^(2) + y(A)^(2))), carctan(x(A), y(A)))
bib = CurveCartesian(log(sqrt(b^(2) + t^(2))), carctan(t, b), t, -1, 1)
B': (log(sqrt(x(B)^(2) + y(B)^(2))), carctan(x(B), y(B)))
I4 = Sequence(CurveCartesian[log(sqrt(b^(2) + t^(2))), carctan(t, b), t, -1, 1], b, -1, 1, 0.1)