Average Error: 0.6 → 1.2
Time: 34.5s
Precision: 64
Internal Precision: 576
\[\log \left(1 + e^{x}\right) - x \cdot y\]
\[\left(\left(\log \left(\sqrt{1 + {\left(e^{x}\right)}^{3}}\right) - \left(\log \left(\sqrt{{\left(e^{x + x}\right)}^{3} + {\left(1 - e^{x}\right)}^{3}}\right) - \log \left(\sqrt{\left(1 - e^{x}\right) \cdot \left(1 - e^{x}\right) - \left(\left(1 - e^{x}\right) - e^{x} \cdot e^{x}\right) \cdot \left(e^{x} \cdot e^{x}\right)}\right)\right)\right) + \frac{1}{2} \cdot \log \left(1 + e^{x}\right)\right) - x \cdot y\]

Error

Bits error versus x

Bits error versus y

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Results

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Target

Original0.6
Target0.1
Herbie1.2
\[\begin{array}{l} \mathbf{if}\;x \le 0:\\ \;\;\;\;\log \left(1 + e^{x}\right) - x \cdot y\\ \mathbf{else}:\\ \;\;\;\;\log \left(1 + e^{-x}\right) - \left(-x\right) \cdot \left(1 - y\right)\\ \end{array}\]

Derivation

  1. Initial program 0.6

    \[\log \left(1 + e^{x}\right) - x \cdot y\]
  2. Using strategy rm
  3. Applied add-sqr-sqrt1.4

    \[\leadsto \log \color{blue}{\left(\sqrt{1 + e^{x}} \cdot \sqrt{1 + e^{x}}\right)} - x \cdot y\]
  4. Applied log-prod1.1

    \[\leadsto \color{blue}{\left(\log \left(\sqrt{1 + e^{x}}\right) + \log \left(\sqrt{1 + e^{x}}\right)\right)} - x \cdot y\]
  5. Using strategy rm
  6. Applied pow1/21.1

    \[\leadsto \left(\log \left(\sqrt{1 + e^{x}}\right) + \log \color{blue}{\left({\left(1 + e^{x}\right)}^{\frac{1}{2}}\right)}\right) - x \cdot y\]
  7. Applied log-pow1.1

    \[\leadsto \left(\log \left(\sqrt{1 + e^{x}}\right) + \color{blue}{\frac{1}{2} \cdot \log \left(1 + e^{x}\right)}\right) - x \cdot y\]
  8. Using strategy rm
  9. Applied flip3-+1.2

    \[\leadsto \left(\log \left(\sqrt{\color{blue}{\frac{{1}^{3} + {\left(e^{x}\right)}^{3}}{1 \cdot 1 + \left(e^{x} \cdot e^{x} - 1 \cdot e^{x}\right)}}}\right) + \frac{1}{2} \cdot \log \left(1 + e^{x}\right)\right) - x \cdot y\]
  10. Applied sqrt-div1.2

    \[\leadsto \left(\log \color{blue}{\left(\frac{\sqrt{{1}^{3} + {\left(e^{x}\right)}^{3}}}{\sqrt{1 \cdot 1 + \left(e^{x} \cdot e^{x} - 1 \cdot e^{x}\right)}}\right)} + \frac{1}{2} \cdot \log \left(1 + e^{x}\right)\right) - x \cdot y\]
  11. Applied log-div1.2

    \[\leadsto \left(\color{blue}{\left(\log \left(\sqrt{{1}^{3} + {\left(e^{x}\right)}^{3}}\right) - \log \left(\sqrt{1 \cdot 1 + \left(e^{x} \cdot e^{x} - 1 \cdot e^{x}\right)}\right)\right)} + \frac{1}{2} \cdot \log \left(1 + e^{x}\right)\right) - x \cdot y\]
  12. Applied simplify1.2

    \[\leadsto \left(\left(\color{blue}{\log \left(\sqrt{1 + {\left(e^{x}\right)}^{3}}\right)} - \log \left(\sqrt{1 \cdot 1 + \left(e^{x} \cdot e^{x} - 1 \cdot e^{x}\right)}\right)\right) + \frac{1}{2} \cdot \log \left(1 + e^{x}\right)\right) - x \cdot y\]
  13. Applied simplify1.2

    \[\leadsto \left(\left(\log \left(\sqrt{1 + {\left(e^{x}\right)}^{3}}\right) - \color{blue}{\log \left(\sqrt{e^{x + x} + \left(1 - e^{x}\right)}\right)}\right) + \frac{1}{2} \cdot \log \left(1 + e^{x}\right)\right) - x \cdot y\]
  14. Using strategy rm
  15. Applied flip3-+1.2

    \[\leadsto \left(\left(\log \left(\sqrt{1 + {\left(e^{x}\right)}^{3}}\right) - \log \left(\sqrt{\color{blue}{\frac{{\left(e^{x + x}\right)}^{3} + {\left(1 - e^{x}\right)}^{3}}{e^{x + x} \cdot e^{x + x} + \left(\left(1 - e^{x}\right) \cdot \left(1 - e^{x}\right) - e^{x + x} \cdot \left(1 - e^{x}\right)\right)}}}\right)\right) + \frac{1}{2} \cdot \log \left(1 + e^{x}\right)\right) - x \cdot y\]
  16. Applied sqrt-div1.2

    \[\leadsto \left(\left(\log \left(\sqrt{1 + {\left(e^{x}\right)}^{3}}\right) - \log \color{blue}{\left(\frac{\sqrt{{\left(e^{x + x}\right)}^{3} + {\left(1 - e^{x}\right)}^{3}}}{\sqrt{e^{x + x} \cdot e^{x + x} + \left(\left(1 - e^{x}\right) \cdot \left(1 - e^{x}\right) - e^{x + x} \cdot \left(1 - e^{x}\right)\right)}}\right)}\right) + \frac{1}{2} \cdot \log \left(1 + e^{x}\right)\right) - x \cdot y\]
  17. Applied log-div1.2

    \[\leadsto \left(\left(\log \left(\sqrt{1 + {\left(e^{x}\right)}^{3}}\right) - \color{blue}{\left(\log \left(\sqrt{{\left(e^{x + x}\right)}^{3} + {\left(1 - e^{x}\right)}^{3}}\right) - \log \left(\sqrt{e^{x + x} \cdot e^{x + x} + \left(\left(1 - e^{x}\right) \cdot \left(1 - e^{x}\right) - e^{x + x} \cdot \left(1 - e^{x}\right)\right)}\right)\right)}\right) + \frac{1}{2} \cdot \log \left(1 + e^{x}\right)\right) - x \cdot y\]
  18. Applied simplify1.2

    \[\leadsto \left(\left(\log \left(\sqrt{1 + {\left(e^{x}\right)}^{3}}\right) - \left(\log \left(\sqrt{{\left(e^{x + x}\right)}^{3} + {\left(1 - e^{x}\right)}^{3}}\right) - \color{blue}{\log \left(\sqrt{\left(1 - e^{x}\right) \cdot \left(1 - e^{x}\right) - \left(\left(1 - e^{x}\right) - e^{x} \cdot e^{x}\right) \cdot \left(e^{x} \cdot e^{x}\right)}\right)}\right)\right) + \frac{1}{2} \cdot \log \left(1 + e^{x}\right)\right) - x \cdot y\]

Runtime

Time bar (total: 34.5s)Debug logProfile

herbie shell --seed 2018201 
(FPCore (x y)
  :name "Logistic regression 2"

  :herbie-target
  (if (<= x 0) (- (log (+ 1 (exp x))) (* x y)) (- (log (+ 1 (exp (- x)))) (* (- x) (- 1 y))))

  (- (log (+ 1 (exp x))) (* x y)))