Author: 藍邦偉  老師

u = Vector((x(Corner[1.0]), 0.0), (x(Corner[3.0]), 0.0))
v = Vector((0.0, y(Corner[1.0])), (0.0, y(Corner[3.0])))
f(x) = 2.0 * sin(x) + cos(2.0 * x) + 2.0
r = 3.6 (slider from -5 to 5, step 0.1)
a = 3.5 (slider from -10 to 10, step 0.5)
b = -9.5 (slider from -10 to 10, step 0.5)
c = CurveCartesian(r * cos(a * t), r * cos(b * t), t, 0.0, 6.28319)