Fresnel integrals C(x) and S(x) are defined as *C(x) = integral(cos(pi t ^{ 2}/2)dt,0,x)* and

Some sources don't use multiplier before *t ^{ 2}* (in this case, the integral is multiplied by the scaling coefficient), so you should watch closely what integral is being referred to.

**FresnelIntegral** subroutine calculates *C(x)* and *S(x)* using piecewise rational approximation.

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