Average Error: 58.8 → 0.4
Time: 11.4s
Precision: 64
\[-1.700000000000000122124532708767219446599 \cdot 10^{-4} \lt x\]
\[e^{x} - 1\]
↓
\[x + {x}^{2} \cdot \left(\frac{1}{2} + x \cdot \frac{1}{6}\right)\]
e^{x} - 1
↓
x + {x}^{2} \cdot \left(\frac{1}{2} + x \cdot \frac{1}{6}\right)
double f(double x) {
        double r100375 = x;
        double r100376 = exp(r100375);
        double r100377 = 1.0;
        double r100378 = r100376 - r100377;
        return r100378;
}
↓
double f(double x) {
        double r100379 = x;
        double r100380 = 2.0;
        double r100381 = pow(r100379, r100380);
        double r100382 = 0.5;
        double r100383 = 0.16666666666666666;
        double r100384 = r100379 * r100383;
        double r100385 = r100382 + r100384;
        double r100386 = r100381 * r100385;
        double r100387 = r100379 + r100386;
        return r100387;
}

Error

Bits error versus x

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Target

Original58.8
Target0.5
Herbie0.4
\[x \cdot \left(\left(1 + \frac{x}{2}\right) + \frac{x \cdot x}{6}\right)\]

Derivation

  1. Initial program 58.8

    \[e^{x} - 1\]

  2. Taylor expanded around 0 0.4

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

  3. Simplified0.4

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

  4. Final simplification0.4

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

Reproduce

herbie shell --seed 2019195 
(FPCore (x)
  :name "expm1 (example 3.7)"
  :pre (< -0.00017 x)

  :herbie-target
  (* x (+ (+ 1.0 (/ x 2.0)) (/ (* x x) 6.0)))

  (- (exp x) 1.0))