Average Error: 31.1 → 0.3
Time: 19.9s
Precision: 64
Internal Precision: 128
\[\frac{1 - \cos x}{x \cdot x}\]
\[\frac{\frac{\frac{\sin x}{x} \cdot \sin x}{x}}{\cos x + 1}\]

Error

Bits error versus x

Derivation

  1. Initial program 31.1

    \[\frac{1 - \cos x}{x \cdot x}\]
  2. Using strategy rm
  3. Applied flip--31.2

    \[\leadsto \frac{\color{blue}{\frac{1 \cdot 1 - \cos x \cdot \cos x}{1 + \cos x}}}{x \cdot x}\]
  4. Applied associate-/l/31.2

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

    \[\leadsto \frac{\color{blue}{\sin x \cdot \sin x}}{\left(x \cdot x\right) \cdot \left(1 + \cos x\right)}\]
  6. Taylor expanded around inf 15.7

    \[\leadsto \color{blue}{\frac{{\left(\sin x\right)}^{2}}{{x}^{2} \cdot \left(\cos x + 1\right)}}\]
  7. Simplified0.3

    \[\leadsto \color{blue}{\frac{\frac{\sin x}{x} \cdot \frac{\sin x}{x}}{\cos x + 1}}\]
  8. Using strategy rm
  9. Applied associate-*r/0.3

    \[\leadsto \frac{\color{blue}{\frac{\frac{\sin x}{x} \cdot \sin x}{x}}}{\cos x + 1}\]
  10. Final simplification0.3

    \[\leadsto \frac{\frac{\frac{\sin x}{x} \cdot \sin x}{x}}{\cos x + 1}\]

Reproduce

herbie shell --seed 2019089 
(FPCore (x)
  :name "cos2 (problem 3.4.1)"
  (/ (- 1 (cos x)) (* x x)))