Chi
From specialfunctionswiki
The hyperbolic cosine integral $\mathrm{Chi} \colon (0,\infty) \rightarrow \mathbb{R}$ is defined by the formula $$\mathrm{Chi}(z)=-\displaystyle\int_z^{\infty} \dfrac{\mathrm{cosh}(t)}{t} \mathrm{d}t,$$ where $\cosh$ denotes the hyperbolic cosine.
Domain coloring of $\mathrm{Chi}$.
Properties
Derivative of chi
Antiderivative of chi