Expression 4, p15

Average Error: 0.0 → 0.0

Time: 6.3s

Precision: 64

\[5 \le a \le 10 \land 0 \le b \le 0.001\]

Math

\[\left(a + b\right) \cdot \left(a + b\right)\]

↓

\[\mathsf{fma}\left(2 \cdot b, a, \mathsf{fma}\left(a, a, b \cdot b\right)\right)\]

C

double f(double a, double b) {
        double r1793818 = a;
        double r1793819 = b;
        double r1793820 = r1793818 + r1793819;
        double r1793821 = r1793820 * r1793820;
        return r1793821;
}

↓

double f(double a, double b) {
        double r1793822 = 2.0;
        double r1793823 = b;
        double r1793824 = r1793822 * r1793823;
        double r1793825 = a;
        double r1793826 = r1793823 * r1793823;
        double r1793827 = fma(r1793825, r1793825, r1793826);
        double r1793828 = fma(r1793824, r1793825, r1793827);
        return r1793828;
}

Error

Bits error versus a

Bits error versus b

Target

Original	0.0
Target	0.0
Herbie	0.0

\[\left(\left(b \cdot a + b \cdot b\right) + b \cdot a\right) + a \cdot a\]

Derivation

1. Initial program 0.0

   \[\left(a + b\right) \cdot \left(a + b\right)\]

2. Taylor expanded around inf 0.0

   \[\leadsto \color{blue}{{a}^{2} + \left({b}^{2} + 2 \cdot \left(a \cdot b\right)\right)}\]

3. Simplified 0.0

   \[\leadsto \color{blue}{\mathsf{fma}\left(2 \cdot b, a, \mathsf{fma}\left(a, a, b \cdot b\right)\right)}\]

4. Final simplification 0.0

   \[\leadsto \mathsf{fma}\left(2 \cdot b, a, \mathsf{fma}\left(a, a, b \cdot b\right)\right)\]

Reproduce

herbie shell --seed 2019152 +o rules:numerics
(FPCore (a b)
  :name "Expression 4, p15"
  :pre (and (<= 5 a 10) (<= 0 b 0.001))

  :herbie-target
  (+ (+ (+ (* b a) (* b b)) (* b a)) (* a a))

  (* (+ a b) (+ a b)))