Average Error: 0.5 → 0.4
Time: 8.1s
Precision: 64
Internal Precision: 1088
\[\log \left(1 + e^{x}\right) - x \cdot y\]
\[\left(\left(\log_* (1 + e^{x}) - y \cdot x\right) + (\left(-y\right) \cdot x + \left(y \cdot x\right))_*\right) + (\left(-x\right) \cdot y + \left(y \cdot x\right))_*\]

Error

Bits error versus x

Bits error versus y

Target

Original0.5
Target0.0
Herbie0.4
\[\begin{array}{l} \mathbf{if}\;x \le 0:\\ \;\;\;\;\log \left(1 + e^{x}\right) - x \cdot y\\ \mathbf{else}:\\ \;\;\;\;\log \left(1 + e^{-x}\right) - \left(-x\right) \cdot \left(1 - y\right)\\ \end{array}\]

Derivation

  1. Initial program 0.5

    \[\log \left(1 + e^{x}\right) - x \cdot y\]
  2. Initial simplification0.4

    \[\leadsto \log_* (1 + e^{x}) - y \cdot x\]
  3. Using strategy rm
  4. Applied *-un-lft-identity0.4

    \[\leadsto \color{blue}{1 \cdot \log_* (1 + e^{x})} - y \cdot x\]
  5. Applied prod-diff0.4

    \[\leadsto \color{blue}{(1 \cdot \left(\log_* (1 + e^{x})\right) + \left(-x \cdot y\right))_* + (\left(-x\right) \cdot y + \left(x \cdot y\right))_*}\]
  6. Simplified0.4

    \[\leadsto \color{blue}{\left(\log_* (1 + e^{x}) - x \cdot y\right)} + (\left(-x\right) \cdot y + \left(x \cdot y\right))_*\]
  7. Using strategy rm
  8. Applied add-sqr-sqrt1.0

    \[\leadsto \left(\color{blue}{\sqrt{\log_* (1 + e^{x})} \cdot \sqrt{\log_* (1 + e^{x})}} - x \cdot y\right) + (\left(-x\right) \cdot y + \left(x \cdot y\right))_*\]
  9. Applied prod-diff1.0

    \[\leadsto \color{blue}{\left((\left(\sqrt{\log_* (1 + e^{x})}\right) \cdot \left(\sqrt{\log_* (1 + e^{x})}\right) + \left(-y \cdot x\right))_* + (\left(-y\right) \cdot x + \left(y \cdot x\right))_*\right)} + (\left(-x\right) \cdot y + \left(x \cdot y\right))_*\]
  10. Simplified0.4

    \[\leadsto \left(\color{blue}{\left(\log_* (1 + e^{x}) - y \cdot x\right)} + (\left(-y\right) \cdot x + \left(y \cdot x\right))_*\right) + (\left(-x\right) \cdot y + \left(x \cdot y\right))_*\]
  11. Final simplification0.4

    \[\leadsto \left(\left(\log_* (1 + e^{x}) - y \cdot x\right) + (\left(-y\right) \cdot x + \left(y \cdot x\right))_*\right) + (\left(-x\right) \cdot y + \left(y \cdot x\right))_*\]

Runtime

Time bar (total: 8.1s)Debug logProfile

BaselineHerbieOracleSpan%
Regimes0.40.40.20.20%
herbie shell --seed 2018339 +o rules:numerics
(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)))