Function functional_boxplot 

pub fn functional_boxplot(
    data: &FdMatrix,
    method: DepthMethod,
    factor: f64,
) -> Result<FunctionalBoxplotResult, FdarError>

Canonical López-Pintado–Romo depth-fence functional boxplot (numeric only).

Ranks curves by functional_depth, takes the deepest curve as the median, builds the 50% central region as the pointwise envelope of the deepest half, inflates it by factor × (central width) to form the whiskers/fence, and flags any curve that exceeds the fence at any evaluation point as an outlier.

The recommended defaults are method = DepthMethod::ModifiedBand and factor = 1.5; the caller passes both explicitly.

Errors

• InvalidDimension if data is empty or has fewer than 2 curves.
• InvalidParameter if factor is negative or not finite.
• Propagates errors from functional_depth.