Currently, both of the following return false: ```rust (-0.0 as f64).asinh().is_sign_negative() (-0.0 as f32).asinh().is_sign_negative() ``` However, in other languages like [C](https://en.cppreference.com/w/c/numeric/math/asinh), `asinh(-0.0)` would always return `-0.0`. We might need another fast case for 0.0 and -0.0 here: https://github.com/rust-lang/rust/blob/f01b9f803b59f170f5dabaaa8aedc96abe45bfea/src/libstd/f64.rs#L833-L839