Average Error: 61.6 → 2.2
Time: 15.2s
Precision: binary64
\[-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{e^{\frac{\pi}{4} \cdot f} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right)\]
\[1 \cdot \left(4 \cdot \left(0.00347222222222222246 \cdot \left(\frac{{\left({\left({\left(\sqrt[3]{\pi}\right)}^{2}\right)}^{\left(\sqrt{3}\right)} \cdot {\left(\sqrt[3]{\pi}\right)}^{\left(\sqrt{3}\right)}\right)}^{\left(\sqrt{3}\right)}}{4} \cdot \frac{{f}^{4}}{4}\right) + \left(\frac{\log f}{\pi} + \left({\pi}^{3} \cdot \left({f}^{4} \cdot 8.68055555555556 \cdot 10^{-5}\right) - \left(\frac{\log \left(\frac{4}{\pi}\right)}{\pi} + \pi \cdot \left(\left(f \cdot f\right) \cdot 0.020833333333333336\right)\right)\right)\right)\right)\right)\]

Error

Bits error versus f

Derivation

  1. Initial program 61.6

    \[-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{e^{\frac{\pi}{4} \cdot f} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right)\]
  2. Simplified61.6

    \[\leadsto \color{blue}{1 \cdot \left(4 \cdot \frac{-\log \left(\frac{{\left(e^{\frac{\pi}{4}}\right)}^{f} + {\left(e^{\frac{\pi}{4}}\right)}^{\left(-f\right)}}{{\left(e^{\frac{\pi}{4}}\right)}^{f} - {\left(e^{\frac{\pi}{4}}\right)}^{\left(-f\right)}}\right)}{\pi}\right)}\]
  3. Taylor expanded around 0 2.2

    \[\leadsto 1 \cdot \left(4 \cdot \frac{-\log \color{blue}{\left(\left(4 \cdot \frac{1}{\pi \cdot f} + 0.083333333333333343 \cdot \left(f \cdot \pi\right)\right) - 3.472222222222224 \cdot 10^{-4} \cdot \left({f}^{3} \cdot {\pi}^{3}\right)\right)}}{\pi}\right)\]
  4. Simplified2.2

    \[\leadsto 1 \cdot \left(4 \cdot \frac{-\log \color{blue}{\left(\frac{4}{\pi \cdot f} + \left(\pi \cdot \left(f \cdot 0.083333333333333343\right) - {f}^{3} \cdot \left({\pi}^{3} \cdot 3.472222222222224 \cdot 10^{-4}\right)\right)\right)}}{\pi}\right)\]
  5. Taylor expanded around 0 2.2

    \[\leadsto 1 \cdot \left(4 \cdot \color{blue}{\left(\left(0.00347222222222222246 \cdot \frac{{f}^{4} \cdot {\pi}^{3}}{{4}^{2}} + \left(\frac{\log f}{\pi} + 8.68055555555556 \cdot 10^{-5} \cdot \left({f}^{4} \cdot {\pi}^{3}\right)\right)\right) - \left(\frac{\log \left(\frac{4}{\pi}\right)}{\pi} + 0.020833333333333336 \cdot \left({f}^{2} \cdot \pi\right)\right)\right)}\right)\]
  6. Simplified2.2

    \[\leadsto 1 \cdot \left(4 \cdot \color{blue}{\left(0.00347222222222222246 \cdot \left(\frac{{\pi}^{3}}{4} \cdot \frac{{f}^{4}}{4}\right) + \left(\frac{\log f}{\pi} + \left({\pi}^{3} \cdot \left({f}^{4} \cdot 8.68055555555556 \cdot 10^{-5}\right) - \left(\frac{\log \left(\frac{4}{\pi}\right)}{\pi} + \pi \cdot \left(\left(f \cdot f\right) \cdot 0.020833333333333336\right)\right)\right)\right)\right)}\right)\]
  7. Using strategy rm
  8. Applied add-sqr-sqrt2.2

    \[\leadsto 1 \cdot \left(4 \cdot \left(0.00347222222222222246 \cdot \left(\frac{{\pi}^{\color{blue}{\left(\sqrt{3} \cdot \sqrt{3}\right)}}}{4} \cdot \frac{{f}^{4}}{4}\right) + \left(\frac{\log f}{\pi} + \left({\pi}^{3} \cdot \left({f}^{4} \cdot 8.68055555555556 \cdot 10^{-5}\right) - \left(\frac{\log \left(\frac{4}{\pi}\right)}{\pi} + \pi \cdot \left(\left(f \cdot f\right) \cdot 0.020833333333333336\right)\right)\right)\right)\right)\right)\]
  9. Applied pow-unpow2.2

    \[\leadsto 1 \cdot \left(4 \cdot \left(0.00347222222222222246 \cdot \left(\frac{\color{blue}{{\left({\pi}^{\left(\sqrt{3}\right)}\right)}^{\left(\sqrt{3}\right)}}}{4} \cdot \frac{{f}^{4}}{4}\right) + \left(\frac{\log f}{\pi} + \left({\pi}^{3} \cdot \left({f}^{4} \cdot 8.68055555555556 \cdot 10^{-5}\right) - \left(\frac{\log \left(\frac{4}{\pi}\right)}{\pi} + \pi \cdot \left(\left(f \cdot f\right) \cdot 0.020833333333333336\right)\right)\right)\right)\right)\right)\]
  10. Using strategy rm
  11. Applied add-cube-cbrt2.2

    \[\leadsto 1 \cdot \left(4 \cdot \left(0.00347222222222222246 \cdot \left(\frac{{\left({\color{blue}{\left(\left(\sqrt[3]{\pi} \cdot \sqrt[3]{\pi}\right) \cdot \sqrt[3]{\pi}\right)}}^{\left(\sqrt{3}\right)}\right)}^{\left(\sqrt{3}\right)}}{4} \cdot \frac{{f}^{4}}{4}\right) + \left(\frac{\log f}{\pi} + \left({\pi}^{3} \cdot \left({f}^{4} \cdot 8.68055555555556 \cdot 10^{-5}\right) - \left(\frac{\log \left(\frac{4}{\pi}\right)}{\pi} + \pi \cdot \left(\left(f \cdot f\right) \cdot 0.020833333333333336\right)\right)\right)\right)\right)\right)\]
  12. Applied unpow-prod-down2.2

    \[\leadsto 1 \cdot \left(4 \cdot \left(0.00347222222222222246 \cdot \left(\frac{{\color{blue}{\left({\left(\sqrt[3]{\pi} \cdot \sqrt[3]{\pi}\right)}^{\left(\sqrt{3}\right)} \cdot {\left(\sqrt[3]{\pi}\right)}^{\left(\sqrt{3}\right)}\right)}}^{\left(\sqrt{3}\right)}}{4} \cdot \frac{{f}^{4}}{4}\right) + \left(\frac{\log f}{\pi} + \left({\pi}^{3} \cdot \left({f}^{4} \cdot 8.68055555555556 \cdot 10^{-5}\right) - \left(\frac{\log \left(\frac{4}{\pi}\right)}{\pi} + \pi \cdot \left(\left(f \cdot f\right) \cdot 0.020833333333333336\right)\right)\right)\right)\right)\right)\]
  13. Simplified2.2

    \[\leadsto 1 \cdot \left(4 \cdot \left(0.00347222222222222246 \cdot \left(\frac{{\left(\color{blue}{{\left({\left(\sqrt[3]{\pi}\right)}^{2}\right)}^{\left(\sqrt{3}\right)}} \cdot {\left(\sqrt[3]{\pi}\right)}^{\left(\sqrt{3}\right)}\right)}^{\left(\sqrt{3}\right)}}{4} \cdot \frac{{f}^{4}}{4}\right) + \left(\frac{\log f}{\pi} + \left({\pi}^{3} \cdot \left({f}^{4} \cdot 8.68055555555556 \cdot 10^{-5}\right) - \left(\frac{\log \left(\frac{4}{\pi}\right)}{\pi} + \pi \cdot \left(\left(f \cdot f\right) \cdot 0.020833333333333336\right)\right)\right)\right)\right)\right)\]
  14. Final simplification2.2

    \[\leadsto 1 \cdot \left(4 \cdot \left(0.00347222222222222246 \cdot \left(\frac{{\left({\left({\left(\sqrt[3]{\pi}\right)}^{2}\right)}^{\left(\sqrt{3}\right)} \cdot {\left(\sqrt[3]{\pi}\right)}^{\left(\sqrt{3}\right)}\right)}^{\left(\sqrt{3}\right)}}{4} \cdot \frac{{f}^{4}}{4}\right) + \left(\frac{\log f}{\pi} + \left({\pi}^{3} \cdot \left({f}^{4} \cdot 8.68055555555556 \cdot 10^{-5}\right) - \left(\frac{\log \left(\frac{4}{\pi}\right)}{\pi} + \pi \cdot \left(\left(f \cdot f\right) \cdot 0.020833333333333336\right)\right)\right)\right)\right)\right)\]

Reproduce

herbie shell --seed 2020179 
(FPCore (f)
  :name "VandenBroeck and Keller, Equation (20)"
  :precision binary64
  (neg (* (/ 1.0 (/ PI 4.0)) (log (/ (+ (exp (* (/ PI 4.0) f)) (exp (neg (* (/ PI 4.0) f)))) (- (exp (* (/ PI 4.0) f)) (exp (neg (* (/ PI 4.0) f)))))))))