地域防犯環境設計（CPTED）と安全な拠点・店舗づくりの実践ガイド：物理的セキュリティと情報セキュリティの統合設計

{`//! Integrated CPTED Illuminance Uniformity & Cyber Surface Hygiene Evaluator.

#[derive(Debug, Clone, Copy)]
pub struct LuminanceGridSummary {
    pub min_lx: f64,
    pub avg_lx: f64,
    pub uniformity_u0: f64,
    pub passes_jis_z9126: bool,
}

/// Computes horizontal illuminance E_h [lx] along a 1D street span [0, span_m]
/// lit by two lamps at x = 0 and x = span_m with mounting height h_m and intensity i_cd.
pub fn evaluate_street_span(span_m: f64, h_m: f64, i_cd: f64, maintenance: f64) -> LuminanceGridSummary {
    let steps = 50usize;
    let mut sum_lx = 0.0_f64;
    let mut min_lx = f64::INFINITY;
    let m = maintenance.clamp(0.1, 1.0);

    for idx in 0..=steps {
        let x = (idx as f64 / steps as f64) * span_m;
        let r1_sq = x * x;
        let r2_sq = (span_m - x) * (span_m - x);
        let e1 = m * (i_cd * h_m) / (h_m * h_m + r1_sq).powf(1.5);
        let e2 = m * (i_cd * h_m) / (h_m * h_m + r2_sq).powf(1.5);
        let e_total = e1 + e2;
        if e_total < min_lx {
            min_lx = e_total;
        }
        sum_lx += e_total;
    }

    let avg_lx = sum_lx / ((steps + 1) as f64);
    let uniformity_u0 = if avg_lx > 0.0 { min_lx / avg_lx } else { 0.0 };

    LuminanceGridSummary {
        min_lx,
        avg_lx,
        uniformity_u0,
        passes_jis_z9126: avg_lx >= 5.0 && min_lx >= 1.0 && uniformity_u0 >= 0.20,
    }
}`}