Average Error: 30.2 → 0.1
Time: 7.4m
Precision: 64
Internal Precision: 128
\[\frac{1 - \cos x}{x \cdot x}\]
\[\frac{\frac{\sin \left(x \cdot \frac{1}{2}\right)}{x}}{\frac{\cos \left(x \cdot \frac{1}{2}\right)}{\frac{\sin x}{x}}}\]

Error

Bits error versus x

Derivation

  1. Initial program 30.2

    \[\frac{1 - \cos x}{x \cdot x}\]
  2. Using strategy rm
  3. Applied flip--30.3

    \[\leadsto \frac{\color{blue}{\frac{1 \cdot 1 - \cos x \cdot \cos x}{1 + \cos x}}}{x \cdot x}\]
  4. Applied associate-/l/30.3

    \[\leadsto \color{blue}{\frac{1 \cdot 1 - \cos x \cdot \cos x}{\left(x \cdot x\right) \cdot \left(1 + \cos x\right)}}\]
  5. Simplified15.0

    \[\leadsto \frac{\color{blue}{\sin x \cdot \sin x}}{\left(x \cdot x\right) \cdot \left(1 + \cos x\right)}\]
  6. Using strategy rm
  7. Applied add-sqr-sqrt38.8

    \[\leadsto \frac{\sin x \cdot \sin x}{\left(x \cdot \color{blue}{\left(\sqrt{x} \cdot \sqrt{x}\right)}\right) \cdot \left(1 + \cos x\right)}\]
  8. Applied add-sqr-sqrt38.9

    \[\leadsto \frac{\sin x \cdot \sin x}{\left(\color{blue}{\left(\sqrt{x} \cdot \sqrt{x}\right)} \cdot \left(\sqrt{x} \cdot \sqrt{x}\right)\right) \cdot \left(1 + \cos x\right)}\]
  9. Applied swap-sqr38.9

    \[\leadsto \frac{\sin x \cdot \sin x}{\color{blue}{\left(\left(\sqrt{x} \cdot \sqrt{x}\right) \cdot \left(\sqrt{x} \cdot \sqrt{x}\right)\right)} \cdot \left(1 + \cos x\right)}\]
  10. Applied associate-*l*39.0

    \[\leadsto \frac{\sin x \cdot \sin x}{\color{blue}{\left(\sqrt{x} \cdot \sqrt{x}\right) \cdot \left(\left(\sqrt{x} \cdot \sqrt{x}\right) \cdot \left(1 + \cos x\right)\right)}}\]
  11. Applied *-un-lft-identity39.0

    \[\leadsto \frac{\sin x \cdot \color{blue}{\left(1 \cdot \sin x\right)}}{\left(\sqrt{x} \cdot \sqrt{x}\right) \cdot \left(\left(\sqrt{x} \cdot \sqrt{x}\right) \cdot \left(1 + \cos x\right)\right)}\]
  12. Applied associate-*r*39.0

    \[\leadsto \frac{\color{blue}{\left(\sin x \cdot 1\right) \cdot \sin x}}{\left(\sqrt{x} \cdot \sqrt{x}\right) \cdot \left(\left(\sqrt{x} \cdot \sqrt{x}\right) \cdot \left(1 + \cos x\right)\right)}\]
  13. Applied times-frac31.6

    \[\leadsto \color{blue}{\frac{\sin x \cdot 1}{\sqrt{x} \cdot \sqrt{x}} \cdot \frac{\sin x}{\left(\sqrt{x} \cdot \sqrt{x}\right) \cdot \left(1 + \cos x\right)}}\]
  14. Simplified31.5

    \[\leadsto \color{blue}{\frac{\sin x}{x}} \cdot \frac{\sin x}{\left(\sqrt{x} \cdot \sqrt{x}\right) \cdot \left(1 + \cos x\right)}\]
  15. Simplified0.1

    \[\leadsto \frac{\sin x}{x} \cdot \color{blue}{\frac{\tan \left(\frac{x}{2}\right)}{x}}\]
  16. Taylor expanded around -inf 15.0

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

    \[\leadsto \color{blue}{\frac{\frac{\sin \left(x \cdot \frac{1}{2}\right)}{x}}{\frac{\cos \left(x \cdot \frac{1}{2}\right)}{\frac{\sin x}{x}}}}\]
  18. Final simplification0.1

    \[\leadsto \frac{\frac{\sin \left(x \cdot \frac{1}{2}\right)}{x}}{\frac{\cos \left(x \cdot \frac{1}{2}\right)}{\frac{\sin x}{x}}}\]

Reproduce

herbie shell --seed 2019088 
(FPCore (x)
  :name "cos2 (problem 3.4.1)"
  (/ (- 1 (cos x)) (* x x)))