DOC: Enhance doc of ADFn
@@ -1055,19 +1055,27 @@ impl Div<AD> for f64 {
/// fn main() {
/// let ad0 = 2f64;
/// let ad1 = AD1(2f64, 1f64);
+/// let ad2 = AD2(2f64, 1f64, 0f64);
///
/// let f_ad = ADFn::new(f);
///
-/// let ans_ad0 = ad0.powi(2);
-/// let ans_ad1 = ad1.powi(2).dx();
+/// let ans0 = ad0.powi(2);
+/// let ans1 = ad1.powi(2).dx();
+/// let ans2 = ad2.powi(2).ddx();
///
-/// assert_eq!(ans_ad0, f_ad.call_stable(ad0));
+/// assert_eq!(ans0, f_ad.call_stable(ad0));
///
-/// let f_grad = f_ad.grad();
-/// assert_eq!(ans_ad1, f_grad.call_stable(ad0));
+/// let df = f_ad.grad();
+/// assert_eq!(ans1, df.call_stable(ad0));
///
-/// let ad_output = f_ad.call_stable(ad1);
-/// assert_eq!(ad_output, AD1(4f64, 4f64));
+/// let ddf = df.grad();
+/// assert_eq!(ans2, ddf.call_stable(ad0));
+///
+/// let ad1_output = f_ad.call_stable(ad1);
+/// assert_eq!(ad1_output, AD1(4f64, 4f64));
+///
+/// let ad2_output = f_ad.call_stable(ad2);
+/// assert_eq!(ad2_output, AD2(4f64, 4f64, 2f64));
/// }
///
/// fn f(x: AD) -> AD {
