Average Error: 0.0 → 0.0
Time: 4.9m
Precision: 64
Internal Precision: 128
\[\frac{1 + \left(2 - \frac{\frac{2}{t}}{1 + \frac{1}{t}}\right) \cdot \left(2 - \frac{\frac{2}{t}}{1 + \frac{1}{t}}\right)}{2 + \left(2 - \frac{\frac{2}{t}}{1 + \frac{1}{t}}\right) \cdot \left(2 - \frac{\frac{2}{t}}{1 + \frac{1}{t}}\right)}\]
\[\frac{(\left((t \cdot \left(\frac{2}{1 - t \cdot t}\right) + \left(2 - \frac{2}{1 - t \cdot t}\right))_*\right) \cdot \left(\log \left(\frac{e^{2}}{e^{\frac{2}{t + 1}}}\right)\right) + 1)_*}{(\left(2 - \frac{2}{t + 1}\right) \cdot \left(2 - \frac{2}{t + 1}\right) + 2)_*}\]

Error

Bits error versus t

Derivation

  1. Initial program 0.0

    \[\frac{1 + \left(2 - \frac{\frac{2}{t}}{1 + \frac{1}{t}}\right) \cdot \left(2 - \frac{\frac{2}{t}}{1 + \frac{1}{t}}\right)}{2 + \left(2 - \frac{\frac{2}{t}}{1 + \frac{1}{t}}\right) \cdot \left(2 - \frac{\frac{2}{t}}{1 + \frac{1}{t}}\right)}\]
  2. Simplified0.0

    \[\leadsto \color{blue}{\frac{(\left(2 - \frac{2}{1 + t}\right) \cdot \left(2 - \frac{2}{1 + t}\right) + 1)_*}{(\left(2 - \frac{2}{1 + t}\right) \cdot \left(2 - \frac{2}{1 + t}\right) + 2)_*}}\]
  3. Using strategy rm
  4. Applied add-log-exp0.0

    \[\leadsto \frac{(\left(2 - \frac{2}{1 + t}\right) \cdot \left(2 - \color{blue}{\log \left(e^{\frac{2}{1 + t}}\right)}\right) + 1)_*}{(\left(2 - \frac{2}{1 + t}\right) \cdot \left(2 - \frac{2}{1 + t}\right) + 2)_*}\]
  5. Applied add-log-exp0.0

    \[\leadsto \frac{(\left(2 - \frac{2}{1 + t}\right) \cdot \left(\color{blue}{\log \left(e^{2}\right)} - \log \left(e^{\frac{2}{1 + t}}\right)\right) + 1)_*}{(\left(2 - \frac{2}{1 + t}\right) \cdot \left(2 - \frac{2}{1 + t}\right) + 2)_*}\]
  6. Applied diff-log0.0

    \[\leadsto \frac{(\left(2 - \frac{2}{1 + t}\right) \cdot \color{blue}{\left(\log \left(\frac{e^{2}}{e^{\frac{2}{1 + t}}}\right)\right)} + 1)_*}{(\left(2 - \frac{2}{1 + t}\right) \cdot \left(2 - \frac{2}{1 + t}\right) + 2)_*}\]
  7. Using strategy rm
  8. Applied flip-+0.0

    \[\leadsto \frac{(\left(2 - \frac{2}{\color{blue}{\frac{1 \cdot 1 - t \cdot t}{1 - t}}}\right) \cdot \left(\log \left(\frac{e^{2}}{e^{\frac{2}{1 + t}}}\right)\right) + 1)_*}{(\left(2 - \frac{2}{1 + t}\right) \cdot \left(2 - \frac{2}{1 + t}\right) + 2)_*}\]
  9. Applied associate-/r/0.0

    \[\leadsto \frac{(\left(2 - \color{blue}{\frac{2}{1 \cdot 1 - t \cdot t} \cdot \left(1 - t\right)}\right) \cdot \left(\log \left(\frac{e^{2}}{e^{\frac{2}{1 + t}}}\right)\right) + 1)_*}{(\left(2 - \frac{2}{1 + t}\right) \cdot \left(2 - \frac{2}{1 + t}\right) + 2)_*}\]
  10. Applied add-cube-cbrt0.8

    \[\leadsto \frac{(\left(\color{blue}{\left(\sqrt[3]{2} \cdot \sqrt[3]{2}\right) \cdot \sqrt[3]{2}} - \frac{2}{1 \cdot 1 - t \cdot t} \cdot \left(1 - t\right)\right) \cdot \left(\log \left(\frac{e^{2}}{e^{\frac{2}{1 + t}}}\right)\right) + 1)_*}{(\left(2 - \frac{2}{1 + t}\right) \cdot \left(2 - \frac{2}{1 + t}\right) + 2)_*}\]
  11. Applied prod-diff0.8

    \[\leadsto \frac{(\color{blue}{\left((\left(\sqrt[3]{2} \cdot \sqrt[3]{2}\right) \cdot \left(\sqrt[3]{2}\right) + \left(-\left(1 - t\right) \cdot \frac{2}{1 \cdot 1 - t \cdot t}\right))_* + (\left(-\left(1 - t\right)\right) \cdot \left(\frac{2}{1 \cdot 1 - t \cdot t}\right) + \left(\left(1 - t\right) \cdot \frac{2}{1 \cdot 1 - t \cdot t}\right))_*\right)} \cdot \left(\log \left(\frac{e^{2}}{e^{\frac{2}{1 + t}}}\right)\right) + 1)_*}{(\left(2 - \frac{2}{1 + t}\right) \cdot \left(2 - \frac{2}{1 + t}\right) + 2)_*}\]
  12. Simplified0.0

    \[\leadsto \frac{(\left(\color{blue}{(t \cdot \left(\frac{2}{1 - t \cdot t}\right) + \left(2 - \frac{2}{1 - t \cdot t}\right))_*} + (\left(-\left(1 - t\right)\right) \cdot \left(\frac{2}{1 \cdot 1 - t \cdot t}\right) + \left(\left(1 - t\right) \cdot \frac{2}{1 \cdot 1 - t \cdot t}\right))_*\right) \cdot \left(\log \left(\frac{e^{2}}{e^{\frac{2}{1 + t}}}\right)\right) + 1)_*}{(\left(2 - \frac{2}{1 + t}\right) \cdot \left(2 - \frac{2}{1 + t}\right) + 2)_*}\]
  13. Simplified0.0

    \[\leadsto \frac{(\left((t \cdot \left(\frac{2}{1 - t \cdot t}\right) + \left(2 - \frac{2}{1 - t \cdot t}\right))_* + \color{blue}{0}\right) \cdot \left(\log \left(\frac{e^{2}}{e^{\frac{2}{1 + t}}}\right)\right) + 1)_*}{(\left(2 - \frac{2}{1 + t}\right) \cdot \left(2 - \frac{2}{1 + t}\right) + 2)_*}\]
  14. Final simplification0.0

    \[\leadsto \frac{(\left((t \cdot \left(\frac{2}{1 - t \cdot t}\right) + \left(2 - \frac{2}{1 - t \cdot t}\right))_*\right) \cdot \left(\log \left(\frac{e^{2}}{e^{\frac{2}{t + 1}}}\right)\right) + 1)_*}{(\left(2 - \frac{2}{t + 1}\right) \cdot \left(2 - \frac{2}{t + 1}\right) + 2)_*}\]

Reproduce

herbie shell --seed 2019088 +o rules:numerics
(FPCore (t)
  :name "Kahan p13 Example 2"
  (/ (+ 1 (* (- 2 (/ (/ 2 t) (+ 1 (/ 1 t)))) (- 2 (/ (/ 2 t) (+ 1 (/ 1 t)))))) (+ 2 (* (- 2 (/ (/ 2 t) (+ 1 (/ 1 t)))) (- 2 (/ (/ 2 t) (+ 1 (/ 1 t))))))))