Holomorphic at a cusp
= Holomorphic at a cusp
A modular function is holomorphic at a cusp when its expansion in the corresponding local parameter has no negative powers. It vanishes at the cusp when that expansion has zero constant term.
= Holomorphic at a cusp
A modular function is holomorphic at a cusp when its expansion in the corresponding local parameter has no negative powers. It vanishes at the cusp when that expansion has zero constant term.