Function extrema_curve_curve 

pub fn extrema_curve_curve(
    a: &Curve,
    b: &Curve,
    options: ExtremaOptions,
    tol: Tolerances,
) -> OgeomResult<Extrema<f64, f64>>

The stationary approaches between two curves.

Line/line is answered in closed form, parallel included; everything else is seeded from a distance grid over both domains and polished by Newton on the stationarity system.

Errors

OgeomError::Construction if the options are unusable; OgeomError::Domain if a curve’s domain is too wide to sample; trim it before asking.