Function point_is_finite

src/plot_state.rs:1076–1078

([x, y]: [f64; 2])

fn find_segment_covering_x(points: &[[f64; 2]], x: f64) -> Option<usize> {
    if points.len() < 2 {
        return None;
    }
    let eps = 1e-12;
    let mut idx = 0usize;
    while idx + 1 < points.len() {