Trigonometric integral
= Trigonometric integral
{title2=$\operatorname{Si}(x),\ \operatorname{Ci}(x)$}
{wiki}
The sine and cosine integrals accumulate $\sin t/t$ and $\cos t/t$, with different normalizations at zero and infinity. They arise in <oscillatory integrals>, <Fourier transforms> of singular kernels and <Fourier series> of logarithmic profiles.