Average Error: 3.9 → 1.7
Time: 4.2m
Precision: 64
Internal Precision: 1856
\[\frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c_p} \cdot {\left(1 - \frac{1}{1 + e^{-s}}\right)}^{c_n}}{{\left(\frac{1}{1 + e^{-t}}\right)}^{c_p} \cdot {\left(1 - \frac{1}{1 + e^{-t}}\right)}^{c_n}}\]
\[e^{\left(\log \left(e^{-t} + 1\right) - \log \left(1 + e^{-s}\right)\right) \cdot c_p - c_n \cdot \left(\log \left({1}^{3} - {\left(\frac{1}{e^{-t} + 1}\right)}^{3}\right) - \left(\log \left(\left(\frac{1}{e^{-t} + 1} + 1\right) + \frac{1}{e^{-t} + 1} \cdot \frac{1}{e^{-t} + 1}\right) + \log \left(1 - \frac{1}{e^{-s} + 1}\right)\right)\right)}\]

Error

Bits error versus c_p

Bits error versus c_n

Bits error versus t

Bits error versus s

Target

Original3.9
Target2.0
Herbie1.7
\[{\left(\frac{1 + e^{-t}}{1 + e^{-s}}\right)}^{c_p} \cdot {\left(\frac{1 + e^{t}}{1 + e^{s}}\right)}^{c_n}\]

Derivation

  1. Initial program 3.9

    \[\frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c_p} \cdot {\left(1 - \frac{1}{1 + e^{-s}}\right)}^{c_n}}{{\left(\frac{1}{1 + e^{-t}}\right)}^{c_p} \cdot {\left(1 - \frac{1}{1 + e^{-t}}\right)}^{c_n}}\]
  2. Using strategy rm
  3. Applied add-exp-log3.9

    \[\leadsto \frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c_p} \cdot {\left(1 - \frac{1}{1 + e^{-s}}\right)}^{c_n}}{{\left(\frac{1}{1 + e^{-t}}\right)}^{c_p} \cdot {\color{blue}{\left(e^{\log \left(1 - \frac{1}{1 + e^{-t}}\right)}\right)}}^{c_n}}\]
  4. Applied pow-exp4.0

    \[\leadsto \frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c_p} \cdot {\left(1 - \frac{1}{1 + e^{-s}}\right)}^{c_n}}{{\left(\frac{1}{1 + e^{-t}}\right)}^{c_p} \cdot \color{blue}{e^{\log \left(1 - \frac{1}{1 + e^{-t}}\right) \cdot c_n}}}\]
  5. Applied add-exp-log4.0

    \[\leadsto \frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c_p} \cdot {\left(1 - \frac{1}{1 + e^{-s}}\right)}^{c_n}}{{\left(\frac{1}{\color{blue}{e^{\log \left(1 + e^{-t}\right)}}}\right)}^{c_p} \cdot e^{\log \left(1 - \frac{1}{1 + e^{-t}}\right) \cdot c_n}}\]
  6. Applied rec-exp4.0

    \[\leadsto \frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c_p} \cdot {\left(1 - \frac{1}{1 + e^{-s}}\right)}^{c_n}}{{\color{blue}{\left(e^{-\log \left(1 + e^{-t}\right)}\right)}}^{c_p} \cdot e^{\log \left(1 - \frac{1}{1 + e^{-t}}\right) \cdot c_n}}\]
  7. Applied pow-exp4.0

    \[\leadsto \frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c_p} \cdot {\left(1 - \frac{1}{1 + e^{-s}}\right)}^{c_n}}{\color{blue}{e^{\left(-\log \left(1 + e^{-t}\right)\right) \cdot c_p}} \cdot e^{\log \left(1 - \frac{1}{1 + e^{-t}}\right) \cdot c_n}}\]
  8. Applied prod-exp4.0

    \[\leadsto \frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c_p} \cdot {\left(1 - \frac{1}{1 + e^{-s}}\right)}^{c_n}}{\color{blue}{e^{\left(-\log \left(1 + e^{-t}\right)\right) \cdot c_p + \log \left(1 - \frac{1}{1 + e^{-t}}\right) \cdot c_n}}}\]
  9. Applied add-exp-log4.0

    \[\leadsto \frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c_p} \cdot {\color{blue}{\left(e^{\log \left(1 - \frac{1}{1 + e^{-s}}\right)}\right)}}^{c_n}}{e^{\left(-\log \left(1 + e^{-t}\right)\right) \cdot c_p + \log \left(1 - \frac{1}{1 + e^{-t}}\right) \cdot c_n}}\]
  10. Applied pow-exp4.0

    \[\leadsto \frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c_p} \cdot \color{blue}{e^{\log \left(1 - \frac{1}{1 + e^{-s}}\right) \cdot c_n}}}{e^{\left(-\log \left(1 + e^{-t}\right)\right) \cdot c_p + \log \left(1 - \frac{1}{1 + e^{-t}}\right) \cdot c_n}}\]
  11. Applied add-exp-log4.0

    \[\leadsto \frac{{\left(\frac{1}{\color{blue}{e^{\log \left(1 + e^{-s}\right)}}}\right)}^{c_p} \cdot e^{\log \left(1 - \frac{1}{1 + e^{-s}}\right) \cdot c_n}}{e^{\left(-\log \left(1 + e^{-t}\right)\right) \cdot c_p + \log \left(1 - \frac{1}{1 + e^{-t}}\right) \cdot c_n}}\]
  12. Applied rec-exp4.0

    \[\leadsto \frac{{\color{blue}{\left(e^{-\log \left(1 + e^{-s}\right)}\right)}}^{c_p} \cdot e^{\log \left(1 - \frac{1}{1 + e^{-s}}\right) \cdot c_n}}{e^{\left(-\log \left(1 + e^{-t}\right)\right) \cdot c_p + \log \left(1 - \frac{1}{1 + e^{-t}}\right) \cdot c_n}}\]
  13. Applied pow-exp3.9

    \[\leadsto \frac{\color{blue}{e^{\left(-\log \left(1 + e^{-s}\right)\right) \cdot c_p}} \cdot e^{\log \left(1 - \frac{1}{1 + e^{-s}}\right) \cdot c_n}}{e^{\left(-\log \left(1 + e^{-t}\right)\right) \cdot c_p + \log \left(1 - \frac{1}{1 + e^{-t}}\right) \cdot c_n}}\]
  14. Applied prod-exp3.9

    \[\leadsto \frac{\color{blue}{e^{\left(-\log \left(1 + e^{-s}\right)\right) \cdot c_p + \log \left(1 - \frac{1}{1 + e^{-s}}\right) \cdot c_n}}}{e^{\left(-\log \left(1 + e^{-t}\right)\right) \cdot c_p + \log \left(1 - \frac{1}{1 + e^{-t}}\right) \cdot c_n}}\]
  15. Applied div-exp1.7

    \[\leadsto \color{blue}{e^{\left(\left(-\log \left(1 + e^{-s}\right)\right) \cdot c_p + \log \left(1 - \frac{1}{1 + e^{-s}}\right) \cdot c_n\right) - \left(\left(-\log \left(1 + e^{-t}\right)\right) \cdot c_p + \log \left(1 - \frac{1}{1 + e^{-t}}\right) \cdot c_n\right)}}\]
  16. Applied simplify1.7

    \[\leadsto e^{\color{blue}{\left(\log \left(e^{-t} + 1\right) - \log \left(1 + e^{-s}\right)\right) \cdot c_p - c_n \cdot \left(\log \left(1 - \frac{1}{e^{-t} + 1}\right) - \log \left(1 - \frac{1}{1 + e^{-s}}\right)\right)}}\]
  17. Using strategy rm
  18. Applied flip3--1.7

    \[\leadsto e^{\left(\log \left(e^{-t} + 1\right) - \log \left(1 + e^{-s}\right)\right) \cdot c_p - c_n \cdot \left(\log \color{blue}{\left(\frac{{1}^{3} - {\left(\frac{1}{e^{-t} + 1}\right)}^{3}}{1 \cdot 1 + \left(\frac{1}{e^{-t} + 1} \cdot \frac{1}{e^{-t} + 1} + 1 \cdot \frac{1}{e^{-t} + 1}\right)}\right)} - \log \left(1 - \frac{1}{1 + e^{-s}}\right)\right)}\]
  19. Applied log-div1.7

    \[\leadsto e^{\left(\log \left(e^{-t} + 1\right) - \log \left(1 + e^{-s}\right)\right) \cdot c_p - c_n \cdot \left(\color{blue}{\left(\log \left({1}^{3} - {\left(\frac{1}{e^{-t} + 1}\right)}^{3}\right) - \log \left(1 \cdot 1 + \left(\frac{1}{e^{-t} + 1} \cdot \frac{1}{e^{-t} + 1} + 1 \cdot \frac{1}{e^{-t} + 1}\right)\right)\right)} - \log \left(1 - \frac{1}{1 + e^{-s}}\right)\right)}\]
  20. Applied associate--l-1.7

    \[\leadsto e^{\left(\log \left(e^{-t} + 1\right) - \log \left(1 + e^{-s}\right)\right) \cdot c_p - c_n \cdot \color{blue}{\left(\log \left({1}^{3} - {\left(\frac{1}{e^{-t} + 1}\right)}^{3}\right) - \left(\log \left(1 \cdot 1 + \left(\frac{1}{e^{-t} + 1} \cdot \frac{1}{e^{-t} + 1} + 1 \cdot \frac{1}{e^{-t} + 1}\right)\right) + \log \left(1 - \frac{1}{1 + e^{-s}}\right)\right)\right)}}\]
  21. Applied simplify1.7

    \[\leadsto e^{\left(\log \left(e^{-t} + 1\right) - \log \left(1 + e^{-s}\right)\right) \cdot c_p - c_n \cdot \left(\log \left({1}^{3} - {\left(\frac{1}{e^{-t} + 1}\right)}^{3}\right) - \color{blue}{\left(\log \left(\left(\frac{1}{e^{-t} + 1} + 1\right) + \frac{1}{e^{-t} + 1} \cdot \frac{1}{e^{-t} + 1}\right) + \log \left(1 - \frac{1}{e^{-s} + 1}\right)\right)}\right)}\]

Runtime

Time bar (total: 4.2m)Debug logProfile

herbie shell --seed '#(1071373924 2949776965 1885069702 3247780810 90874544 2263903749)' 
(FPCore (c_p c_n t s)
  :name "Harley's example"
  :pre (and (< 0 c_p) (< 0 c_n))

  :herbie-target
  (* (pow (/ (+ 1 (exp (- t))) (+ 1 (exp (- s)))) c_p) (pow (/ (+ 1 (exp t)) (+ 1 (exp s))) c_n))

  (/ (* (pow (/ 1 (+ 1 (exp (- s)))) c_p) (pow (- 1 (/ 1 (+ 1 (exp (- s))))) c_n)) (* (pow (/ 1 (+ 1 (exp (- t)))) c_p) (pow (- 1 (/ 1 (+ 1 (exp (- t))))) c_n))))