1 files changed, 8 insertions(+), 4 deletions(-)

M src/adaa.rs

@@ 40,12 40,15 @@ impl Adaa2 {
     fn fallback(x0: f64, x1: f64, x2: f64) -> f64 {
         const A: f64 = 1.0 / 2.0;
         let x_bar = A * (x0 + x2);
-        let delta = x_bar - x1;
+        let delta = x_bar.powi(2) - x1.powi(2);
+        let sum = x_bar + x1;
 
         if Adaa2::is_small(delta) {
             Adaa2::f0(A * (x_bar + x1))
         } else {
-            (2.0 / delta) * (Adaa2::f1(x_bar) + (Adaa2::f2(x1) - Adaa2::f2(x_bar)) / delta)
+            (Adaa2::f1(x_bar) + (Adaa2::f2(x1) - Adaa2::f2(x_bar)) / delta * sum) / delta
+                * 2.0
+                * sum
         }
     }
 


@@ 53,11 56,12 @@ impl Adaa2 {
         let x0 = x0 as f64;
         let x1 = self.x1;
         let x2 = self.x2;
-        let dif = x0 - x2;
+        let dif = x0.powi(2) - x2.powi(2);
+        let sum = x0 + x2;
         let y = if Adaa2::is_small(dif) {
             Adaa2::fallback(x0, x1, x2)
         } else {
-            (2.0 / (dif)) * (Adaa2::calc_d(x0, x1) - Adaa2::calc_d(x1, x2))
+            (Adaa2::calc_d(x0, x1) - Adaa2::calc_d(x1, x2)) / dif * 2.0 * sum
         };
 
         self.x2 = x1;