Fresnel

Fresnel integral implementation according to CEPHES library. See the wikipedia article of Fresnel integral.

Normalized Fresnel integrals of the form with the two asymptotic points (0.5, 0.5) and (-0.5, -0.5): x(l) = int_0^l cos( (pit^2) / 2 ) dt y(l) = int_0^l sin( pit^2) / 2 ) dt