Say I have an incomplete elliptic integral of first kind of the form
$$F(\varphi(z), k(z))=\int_0^{\varphi(z)} \frac{d \theta}{\sqrt{1-k(z)^2 \sin ^2 \theta}}$$
where each arguments are function of some variable $z$.
How do I taylor series $F$ in small z?
Thanks!