Function log1p 

pub fn log1p(x: f64) -> f64

ln(1 + x), accurate for small x.

use mathverse_core::float::log1p;
assert!((log1p(1e-12) - 1e-12).abs() < 1e-24);
assert!((log1p(core::f64::consts::E - 1.0) - 1.0).abs() < 1e-15);