Function domain_selection 

pub fn domain_selection(
    fit: &FregreLmResult,
    window_width: usize,
    threshold: f64,
) -> Result<DomainSelectionResult, FdarError>

Domain selection for a linear functional regression model.

Errors

Returns FdarError::InvalidParameter if beta_t, window_width, or threshold are invalid (e.g., empty beta_t, zero window_width, or window_width exceeding beta_t length).