Average Error: 40.2 → 0.4
Time: 10.7s
Precision: 64
Internal Precision: 128
\[\frac{e^{x}}{e^{x} - 1}\]
\[\frac{\frac{1}{(e^{x} - 1)^*}}{\frac{1}{e^{x}}}\]

Error

Bits error versus x

Target

Original40.2
Target39.8
Herbie0.4
\[\frac{1}{1 - e^{-x}}\]

Derivation

  1. Initial program 40.2

    \[\frac{e^{x}}{e^{x} - 1}\]
  2. Using strategy rm
  3. Applied expm1-def0.4

    \[\leadsto \frac{e^{x}}{\color{blue}{(e^{x} - 1)^*}}\]
  4. Using strategy rm
  5. Applied *-un-lft-identity0.4

    \[\leadsto \frac{\color{blue}{1 \cdot e^{x}}}{(e^{x} - 1)^*}\]
  6. Applied associate-/l*0.4

    \[\leadsto \color{blue}{\frac{1}{\frac{(e^{x} - 1)^*}{e^{x}}}}\]
  7. Using strategy rm
  8. Applied div-inv0.4

    \[\leadsto \frac{1}{\color{blue}{(e^{x} - 1)^* \cdot \frac{1}{e^{x}}}}\]
  9. Applied associate-/r*0.4

    \[\leadsto \color{blue}{\frac{\frac{1}{(e^{x} - 1)^*}}{\frac{1}{e^{x}}}}\]
  10. Final simplification0.4

    \[\leadsto \frac{\frac{1}{(e^{x} - 1)^*}}{\frac{1}{e^{x}}}\]

Reproduce

herbie shell --seed 2019068 +o rules:numerics
(FPCore (x)
  :name "expq2 (section 3.11)"

  :herbie-target
  (/ 1 (- 1 (exp (- x))))

  (/ (exp x) (- (exp x) 1)))