Average Error: 58.7 → 0.4
Time: 12.6s
Precision: 64
\[-1.700000000000000122124532708767219446599 \cdot 10^{-4} \lt x\]
\[e^{x} - 1\]
↓
\[{x}^{2} \cdot \left(\frac{1}{6} \cdot x + \frac{1}{2}\right) + x\]
e^{x} - 1
↓
{x}^{2} \cdot \left(\frac{1}{6} \cdot x + \frac{1}{2}\right) + x
double f(double x) {
        double r89010 = x;
        double r89011 = exp(r89010);
        double r89012 = 1.0;
        double r89013 = r89011 - r89012;
        return r89013;
}
↓
double f(double x) {
        double r89014 = x;
        double r89015 = 2.0;
        double r89016 = pow(r89014, r89015);
        double r89017 = 0.16666666666666666;
        double r89018 = r89017 * r89014;
        double r89019 = 0.5;
        double r89020 = r89018 + r89019;
        double r89021 = r89016 * r89020;
        double r89022 = r89021 + r89014;
        return r89022;
}

Error

Bits error versus x

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Target

Original58.7
Target0.4
Herbie0.4
\[x \cdot \left(\left(1 + \frac{x}{2}\right) + \frac{x \cdot x}{6}\right)\]

Derivation

  1. Initial program 58.7

    \[e^{x} - 1\]

  2. Taylor expanded around 0 0.4

    \[\leadsto \color{blue}{\frac{1}{2} \cdot {x}^{2} + \left(\frac{1}{6} \cdot {x}^{3} + x\right)}\]

  3. Simplified0.4

    \[\leadsto \color{blue}{{x}^{2} \cdot \left(\frac{1}{6} \cdot x + \frac{1}{2}\right) + x}\]

  4. Final simplification0.4

    \[\leadsto {x}^{2} \cdot \left(\frac{1}{6} \cdot x + \frac{1}{2}\right) + x\]

Reproduce

herbie shell --seed 2019325 
(FPCore (x)
  :name "expm1 (example 3.7)"
  :precision binary64
  :pre (< -0.00017 x)

  :herbie-target
  (* x (+ (+ 1 (/ x 2)) (/ (* x x) 6)))

  (- (exp x) 1))