Average Error: 59.2 → 0.1
Time: 37.5s
Precision: 64
Ground Truth: 128
\[e^{x} - 1\]
⬇
\[{x}^2 \cdot \left(\frac{1}{2} + x \cdot \frac{1}{6}\right) + x\]

Error

Bits error versus x

Target

Original59.2
Comparison0.1
Herbie0.1
\[ x \cdot \left(\left(1 + \frac{x}{2}\right) + \frac{{x}^2}{6}\right) \]

Derivation

  1. Initial program 59.2

    \[e^{x} - 1\]

  2. Applied taylor 0.1

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

  3. Taylor expanded around 0 0.1

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

  4. Applied simplify 0.1

    \[\leadsto \color{blue}{{x}^2 \cdot \left(\frac{1}{2} + x \cdot \frac{1}{6}\right) + x}\]
  5. Removed slow pow expressions

Runtime

Total time: 37.5s Debug log

Please include this information when filing a bug report:

herbie --seed '#(419307600 933181845 1298648851 1064993436 1288237649 54622950)'
(FPCore (x)
  :name "NMSE example 3.7"
  :pre (< -0.00017 x)

  :target
  (* x (+ (+ 1 (/ x 2)) (/ (sqr x) 6)))

  (- (exp x) 1))