Average Error: 58.5 → 0.2
Time: 22.1s
Precision: 64
Internal Precision: 1408
\[\frac{1}{2} \cdot \log \left(\frac{1 + x}{1 - x}\right)\]
↓
\[(\left(\frac{\frac{2}{3} \cdot x}{2}\right) \cdot \left(x \cdot x\right) + \left((\left({x}^{5}\right) \cdot \left(\frac{\frac{2}{5}}{2}\right) + x)_*\right))_*\]

Error

Bits error versus x

Derivation

  1. Initial program 58.5

    \[\frac{1}{2} \cdot \log \left(\frac{1 + x}{1 - x}\right)\]

  2. Taylor expanded around 0 0.2

    \[\leadsto \frac{1}{2} \cdot \color{blue}{\left(\frac{2}{3} \cdot {x}^{3} + \left(\frac{2}{5} \cdot {x}^{5} + 2 \cdot x\right)\right)}\]

  3. Applied simplify0.2

    \[\leadsto \color{blue}{(\left(\frac{\frac{2}{3} \cdot x}{2}\right) \cdot \left(x \cdot x\right) + \left((\left({x}^{5}\right) \cdot \left(\frac{\frac{2}{5}}{2}\right) + x)_*\right))_*}\]

Runtime

Time bar (total: 22.1s)Debug logProfile

herbie shell --seed '#(1064397287 3527694221 3797617954 1138343853 2854031332 1153838279)' +o rules:numerics
(FPCore (x)
  :name "Hyperbolic arc-(co)tangent"
  (* (/ 1 2) (log (/ (+ 1 x) (- 1 x)))))