Average Error: 9.6 → 0.1
Time: 1.9m
Precision: 64
Internal Precision: 1088
\[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}\]
\[\frac{\frac{2}{(x \cdot x + x)_*}}{x - 1}\]

Error

Bits error versus x

Target

Original9.6
Target0.2
Herbie0.1
\[\frac{2}{x \cdot \left(x \cdot x - 1\right)}\]

Derivation

  1. Initial program 9.6

    \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}\]
  2. Using strategy rm
  3. Applied frac-sub25.8

    \[\leadsto \color{blue}{\frac{1 \cdot x - \left(x + 1\right) \cdot 2}{\left(x + 1\right) \cdot x}} + \frac{1}{x - 1}\]
  4. Applied frac-add25.1

    \[\leadsto \color{blue}{\frac{\left(1 \cdot x - \left(x + 1\right) \cdot 2\right) \cdot \left(x - 1\right) + \left(\left(x + 1\right) \cdot x\right) \cdot 1}{\left(\left(x + 1\right) \cdot x\right) \cdot \left(x - 1\right)}}\]
  5. Applied simplify25.6

    \[\leadsto \frac{\color{blue}{(\left(x - 1\right) \cdot \left(x - (x \cdot 2 + 2)_*\right) + \left(x \cdot x + x\right))_*}}{\left(\left(x + 1\right) \cdot x\right) \cdot \left(x - 1\right)}\]
  6. Applied simplify25.6

    \[\leadsto \frac{(\left(x - 1\right) \cdot \left(x - (x \cdot 2 + 2)_*\right) + \left(x \cdot x + x\right))_*}{\color{blue}{(x \cdot x + x)_* \cdot \left(x - 1\right)}}\]
  7. Taylor expanded around 0 0.3

    \[\leadsto \frac{\color{blue}{2}}{(x \cdot x + x)_* \cdot \left(x - 1\right)}\]
  8. Using strategy rm
  9. Applied associate-/r*0.1

    \[\leadsto \color{blue}{\frac{\frac{2}{(x \cdot x + x)_*}}{x - 1}}\]

Runtime

Time bar (total: 1.9m)Debug logProfile

herbie shell --seed '#(1071948828 1180510430 2986424009 997076509 406109801 420189285)' +o rules:numerics
(FPCore (x)
  :name "3frac (problem 3.3.3)"

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

  (+ (- (/ 1 (+ x 1)) (/ 2 x)) (/ 1 (- x 1))))