Average Error: 31.3 → 1.1
Time: 19.9s
Precision: 64
Internal Precision: 128
\[\frac{1 - \cos x}{x \cdot x}\]
\[\frac{\sqrt[3]{\sin x} \cdot \sqrt[3]{\sin x}}{x} \cdot \left(\tan \left(\frac{x}{2}\right) \cdot \frac{\sqrt[3]{\sin x}}{x}\right)\]

Error

Bits error versus x

Derivation

  1. Initial program 31.3

    \[\frac{1 - \cos x}{x \cdot x}\]
  2. Using strategy rm
  3. Applied flip--31.4

    \[\leadsto \frac{\color{blue}{\frac{1 \cdot 1 - \cos x \cdot \cos x}{1 + \cos x}}}{x \cdot x}\]
  4. Applied associate-/l/31.4

    \[\leadsto \color{blue}{\frac{1 \cdot 1 - \cos x \cdot \cos x}{\left(x \cdot x\right) \cdot \left(1 + \cos x\right)}}\]
  5. Simplified15.7

    \[\leadsto \frac{\color{blue}{\sin x \cdot \sin x}}{\left(x \cdot x\right) \cdot \left(1 + \cos x\right)}\]
  6. Using strategy rm
  7. Applied times-frac16.0

    \[\leadsto \color{blue}{\frac{\sin x}{x \cdot x} \cdot \frac{\sin x}{1 + \cos x}}\]
  8. Simplified15.9

    \[\leadsto \frac{\sin x}{x \cdot x} \cdot \color{blue}{\tan \left(\frac{x}{2}\right)}\]
  9. Using strategy rm
  10. Applied add-cube-cbrt16.4

    \[\leadsto \frac{\color{blue}{\left(\sqrt[3]{\sin x} \cdot \sqrt[3]{\sin x}\right) \cdot \sqrt[3]{\sin x}}}{x \cdot x} \cdot \tan \left(\frac{x}{2}\right)\]
  11. Applied times-frac1.1

    \[\leadsto \color{blue}{\left(\frac{\sqrt[3]{\sin x} \cdot \sqrt[3]{\sin x}}{x} \cdot \frac{\sqrt[3]{\sin x}}{x}\right)} \cdot \tan \left(\frac{x}{2}\right)\]
  12. Applied associate-*l*1.1

    \[\leadsto \color{blue}{\frac{\sqrt[3]{\sin x} \cdot \sqrt[3]{\sin x}}{x} \cdot \left(\frac{\sqrt[3]{\sin x}}{x} \cdot \tan \left(\frac{x}{2}\right)\right)}\]
  13. Final simplification1.1

    \[\leadsto \frac{\sqrt[3]{\sin x} \cdot \sqrt[3]{\sin x}}{x} \cdot \left(\tan \left(\frac{x}{2}\right) \cdot \frac{\sqrt[3]{\sin x}}{x}\right)\]

Reproduce

herbie shell --seed 2019068 +o rules:numerics
(FPCore (x)
  :name "cos2 (problem 3.4.1)"
  (/ (- 1 (cos x)) (* x x)))