Average Error: 58.8 → 0.3
Time: 4.5s
Precision: 64
\[-1.7 \cdot 10^{-4} \lt x\]
\[e^{x} - 1\]
↓
\[{x}^{2} \cdot \left(\frac{1}{6} \cdot x + \frac{1}{2}\right) + x\]
e^{x} - 1
↓
{x}^{2} \cdot \left(\frac{1}{6} \cdot x + \frac{1}{2}\right) + x
double f(double x) {
        double r94061 = x;
        double r94062 = exp(r94061);
        double r94063 = 1.0;
        double r94064 = r94062 - r94063;
        return r94064;
}
↓
double f(double x) {
        double r94065 = x;
        double r94066 = 2.0;
        double r94067 = pow(r94065, r94066);
        double r94068 = 0.16666666666666666;
        double r94069 = r94068 * r94065;
        double r94070 = 0.5;
        double r94071 = r94069 + r94070;
        double r94072 = r94067 * r94071;
        double r94073 = r94072 + r94065;
        return r94073;
}

Error

Bits error versus x

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Target

Original58.8
Target0.4
Herbie0.3
\[x \cdot \left(\left(1 + \frac{x}{2}\right) + \frac{x \cdot x}{6}\right)\]

Derivation

  1. Initial program 58.8

    \[e^{x} - 1\]

  2. Taylor expanded around 0 0.3

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

  3. Simplified0.3

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

  4. Final simplification0.3

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

Reproduce

herbie shell --seed 2020047 
(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))