Average Error: 0.3 → 0.3
Time: 1.5m
Precision: 64
Internal Precision: 128
\[\left(\left(\log \left(x + y\right) + \log z\right) - t\right) + \left(a - 0.5\right) \cdot \log t\]
\[\left(\left(\left(\log z + \log \left(\sqrt[3]{\sqrt{y + x}}\right)\right) - t\right) + \log t \cdot \left(a - 0.5\right)\right) + \left(\log \left(\sqrt[3]{\sqrt{y + x}} \cdot \sqrt[3]{\sqrt{y + x}}\right) + \log \left(\sqrt{y + x}\right)\right)\]

Error

Bits error versus x

Bits error versus y

Bits error versus z

Bits error versus t

Bits error versus a

Derivation

  1. Initial program 0.3

    \[\left(\left(\log \left(x + y\right) + \log z\right) - t\right) + \left(a - 0.5\right) \cdot \log t\]
  2. Using strategy rm
  3. Applied add-sqr-sqrt0.3

    \[\leadsto \left(\left(\log \color{blue}{\left(\sqrt{x + y} \cdot \sqrt{x + y}\right)} + \log z\right) - t\right) + \left(a - 0.5\right) \cdot \log t\]
  4. Applied log-prod0.3

    \[\leadsto \left(\left(\color{blue}{\left(\log \left(\sqrt{x + y}\right) + \log \left(\sqrt{x + y}\right)\right)} + \log z\right) - t\right) + \left(a - 0.5\right) \cdot \log t\]
  5. Applied associate-+l+0.3

    \[\leadsto \left(\color{blue}{\left(\log \left(\sqrt{x + y}\right) + \left(\log \left(\sqrt{x + y}\right) + \log z\right)\right)} - t\right) + \left(a - 0.5\right) \cdot \log t\]
  6. Applied associate--l+0.3

    \[\leadsto \color{blue}{\left(\log \left(\sqrt{x + y}\right) + \left(\left(\log \left(\sqrt{x + y}\right) + \log z\right) - t\right)\right)} + \left(a - 0.5\right) \cdot \log t\]
  7. Applied associate-+l+0.3

    \[\leadsto \color{blue}{\log \left(\sqrt{x + y}\right) + \left(\left(\left(\log \left(\sqrt{x + y}\right) + \log z\right) - t\right) + \left(a - 0.5\right) \cdot \log t\right)}\]
  8. Using strategy rm
  9. Applied add-cube-cbrt0.3

    \[\leadsto \log \left(\sqrt{x + y}\right) + \left(\left(\left(\log \color{blue}{\left(\left(\sqrt[3]{\sqrt{x + y}} \cdot \sqrt[3]{\sqrt{x + y}}\right) \cdot \sqrt[3]{\sqrt{x + y}}\right)} + \log z\right) - t\right) + \left(a - 0.5\right) \cdot \log t\right)\]
  10. Applied log-prod0.3

    \[\leadsto \log \left(\sqrt{x + y}\right) + \left(\left(\left(\color{blue}{\left(\log \left(\sqrt[3]{\sqrt{x + y}} \cdot \sqrt[3]{\sqrt{x + y}}\right) + \log \left(\sqrt[3]{\sqrt{x + y}}\right)\right)} + \log z\right) - t\right) + \left(a - 0.5\right) \cdot \log t\right)\]
  11. Applied associate-+l+0.3

    \[\leadsto \log \left(\sqrt{x + y}\right) + \left(\left(\color{blue}{\left(\log \left(\sqrt[3]{\sqrt{x + y}} \cdot \sqrt[3]{\sqrt{x + y}}\right) + \left(\log \left(\sqrt[3]{\sqrt{x + y}}\right) + \log z\right)\right)} - t\right) + \left(a - 0.5\right) \cdot \log t\right)\]
  12. Applied associate--l+0.3

    \[\leadsto \log \left(\sqrt{x + y}\right) + \left(\color{blue}{\left(\log \left(\sqrt[3]{\sqrt{x + y}} \cdot \sqrt[3]{\sqrt{x + y}}\right) + \left(\left(\log \left(\sqrt[3]{\sqrt{x + y}}\right) + \log z\right) - t\right)\right)} + \left(a - 0.5\right) \cdot \log t\right)\]
  13. Applied associate-+l+0.3

    \[\leadsto \log \left(\sqrt{x + y}\right) + \color{blue}{\left(\log \left(\sqrt[3]{\sqrt{x + y}} \cdot \sqrt[3]{\sqrt{x + y}}\right) + \left(\left(\left(\log \left(\sqrt[3]{\sqrt{x + y}}\right) + \log z\right) - t\right) + \left(a - 0.5\right) \cdot \log t\right)\right)}\]
  14. Applied associate-+r+0.3

    \[\leadsto \color{blue}{\left(\log \left(\sqrt{x + y}\right) + \log \left(\sqrt[3]{\sqrt{x + y}} \cdot \sqrt[3]{\sqrt{x + y}}\right)\right) + \left(\left(\left(\log \left(\sqrt[3]{\sqrt{x + y}}\right) + \log z\right) - t\right) + \left(a - 0.5\right) \cdot \log t\right)}\]
  15. Final simplification0.3

    \[\leadsto \left(\left(\left(\log z + \log \left(\sqrt[3]{\sqrt{y + x}}\right)\right) - t\right) + \log t \cdot \left(a - 0.5\right)\right) + \left(\log \left(\sqrt[3]{\sqrt{y + x}} \cdot \sqrt[3]{\sqrt{y + x}}\right) + \log \left(\sqrt{y + x}\right)\right)\]

Reproduce

herbie shell --seed 2019088 
(FPCore (x y z t a)
  :name "Numeric.SpecFunctions:logGammaL from math-functions-0.1.5.2"
  (+ (- (+ (log (+ x y)) (log z)) t) (* (- a 0.5) (log t))))