Average Error: 0.5 → 0.3
Time: 1.4m
Precision: 64
\[\frac{1 - 5 \cdot \left(v \cdot v\right)}{\left(\left(\pi \cdot t\right) \cdot \sqrt{2 \cdot \left(1 - 3 \cdot \left(v \cdot v\right)\right)}\right) \cdot \left(1 - v \cdot v\right)}\]
\[\left(\frac{\left(v \cdot v\right) \cdot \frac{v \cdot v}{\sqrt{2} \cdot \pi}}{t} \cdot \frac{-53}{8} + \frac{\frac{1}{\sqrt{2} \cdot \pi}}{t}\right) + \frac{-5}{2} \cdot \frac{v \cdot v}{\left(\sqrt{2} \cdot \pi\right) \cdot t}\]

Error

Bits error versus v

Bits error versus t

Derivation

  1. Initial program 0.5

    \[\frac{1 - 5 \cdot \left(v \cdot v\right)}{\left(\left(\pi \cdot t\right) \cdot \sqrt{2 \cdot \left(1 - 3 \cdot \left(v \cdot v\right)\right)}\right) \cdot \left(1 - v \cdot v\right)}\]
  2. Using strategy rm
  3. Applied associate-*l*0.5

    \[\leadsto \frac{1 - 5 \cdot \left(v \cdot v\right)}{\color{blue}{\left(\pi \cdot \left(t \cdot \sqrt{2 \cdot \left(1 - 3 \cdot \left(v \cdot v\right)\right)}\right)\right)} \cdot \left(1 - v \cdot v\right)}\]
  4. Taylor expanded around 0 0.6

    \[\leadsto \color{blue}{\frac{1}{t \cdot \left(\sqrt{2} \cdot \pi\right)} - \left(\frac{53}{8} \cdot \frac{{v}^{4}}{t \cdot \left(\sqrt{2} \cdot \pi\right)} + \frac{5}{2} \cdot \frac{{v}^{2}}{t \cdot \left(\sqrt{2} \cdot \pi\right)}\right)}\]
  5. Simplified0.6

    \[\leadsto \color{blue}{\frac{v \cdot v}{\left(\sqrt{2} \cdot \pi\right) \cdot t} \cdot \frac{-5}{2} + \left(\frac{1}{\left(\sqrt{2} \cdot \pi\right) \cdot t} + \frac{\frac{v \cdot v}{\sqrt{2} \cdot \pi} \cdot \left(v \cdot v\right)}{t} \cdot \frac{-53}{8}\right)}\]
  6. Using strategy rm
  7. Applied associate-/r*0.3

    \[\leadsto \frac{v \cdot v}{\left(\sqrt{2} \cdot \pi\right) \cdot t} \cdot \frac{-5}{2} + \left(\color{blue}{\frac{\frac{1}{\sqrt{2} \cdot \pi}}{t}} + \frac{\frac{v \cdot v}{\sqrt{2} \cdot \pi} \cdot \left(v \cdot v\right)}{t} \cdot \frac{-53}{8}\right)\]
  8. Final simplification0.3

    \[\leadsto \left(\frac{\left(v \cdot v\right) \cdot \frac{v \cdot v}{\sqrt{2} \cdot \pi}}{t} \cdot \frac{-53}{8} + \frac{\frac{1}{\sqrt{2} \cdot \pi}}{t}\right) + \frac{-5}{2} \cdot \frac{v \cdot v}{\left(\sqrt{2} \cdot \pi\right) \cdot t}\]

Reproduce

herbie shell --seed 2019100 
(FPCore (v t)
  :name "Falkner and Boettcher, Equation (20:1,3)"
  (/ (- 1 (* 5 (* v v))) (* (* (* PI t) (sqrt (* 2 (- 1 (* 3 (* v v)))))) (- 1 (* v v)))))