Average Error: 39.9 → 0.4
Time: 23.0s
Precision: 64
Internal Precision: 128
\[\cos \left(x + \varepsilon\right) - \cos x\]
\[\left((\left(\sin x\right) \cdot \left(\cos \left(\frac{1}{2} \cdot \varepsilon\right)\right) + \left(\sin \left(\frac{1}{2} \cdot \varepsilon\right) \cdot \cos x\right))_* \cdot \sin \left(\frac{1}{2} \cdot \varepsilon\right)\right) \cdot -2\]

Error

Bits error versus x

Bits error versus eps

Derivation

  1. Initial program 39.9

    \[\cos \left(x + \varepsilon\right) - \cos x\]
  2. Initial simplification39.9

    \[\leadsto \cos \left(\varepsilon + x\right) - \cos x\]
  3. Using strategy rm
  4. Applied diff-cos34.6

    \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\frac{\left(\varepsilon + x\right) - x}{2}\right) \cdot \sin \left(\frac{\left(\varepsilon + x\right) + x}{2}\right)\right)}\]
  5. Simplified15.2

    \[\leadsto -2 \cdot \color{blue}{\left(\sin \left(\frac{\left(x + x\right) + \varepsilon}{2}\right) \cdot \sin \left(\frac{\varepsilon}{2}\right)\right)}\]
  6. Taylor expanded around inf 15.2

    \[\leadsto \color{blue}{-2 \cdot \left(\sin \left(\frac{1}{2} \cdot \left(2 \cdot x + \varepsilon\right)\right) \cdot \sin \left(\frac{1}{2} \cdot \varepsilon\right)\right)}\]
  7. Simplified15.1

    \[\leadsto \color{blue}{\left(\sin \left((\varepsilon \cdot \frac{1}{2} + x)_*\right) \cdot \sin \left(\varepsilon \cdot \frac{1}{2}\right)\right) \cdot -2}\]
  8. Using strategy rm
  9. Applied fma-udef15.1

    \[\leadsto \left(\sin \color{blue}{\left(\varepsilon \cdot \frac{1}{2} + x\right)} \cdot \sin \left(\varepsilon \cdot \frac{1}{2}\right)\right) \cdot -2\]
  10. Applied sin-sum0.4

    \[\leadsto \left(\color{blue}{\left(\sin \left(\varepsilon \cdot \frac{1}{2}\right) \cdot \cos x + \cos \left(\varepsilon \cdot \frac{1}{2}\right) \cdot \sin x\right)} \cdot \sin \left(\varepsilon \cdot \frac{1}{2}\right)\right) \cdot -2\]
  11. Taylor expanded around inf 0.4

    \[\leadsto \color{blue}{\left(\sin \left(\frac{1}{2} \cdot \varepsilon\right) \cdot \left(\sin x \cdot \cos \left(\frac{1}{2} \cdot \varepsilon\right) + \cos x \cdot \sin \left(\frac{1}{2} \cdot \varepsilon\right)\right)\right)} \cdot -2\]
  12. Simplified0.4

    \[\leadsto \color{blue}{\left((\left(\sin x\right) \cdot \left(\cos \left(\frac{1}{2} \cdot \varepsilon\right)\right) + \left(\cos x \cdot \sin \left(\frac{1}{2} \cdot \varepsilon\right)\right))_* \cdot \sin \left(\frac{1}{2} \cdot \varepsilon\right)\right)} \cdot -2\]
  13. Final simplification0.4

    \[\leadsto \left((\left(\sin x\right) \cdot \left(\cos \left(\frac{1}{2} \cdot \varepsilon\right)\right) + \left(\sin \left(\frac{1}{2} \cdot \varepsilon\right) \cdot \cos x\right))_* \cdot \sin \left(\frac{1}{2} \cdot \varepsilon\right)\right) \cdot -2\]

Runtime

Time bar (total: 23.0s)Debug logProfile

herbie shell --seed 2018296 +o rules:numerics
(FPCore (x eps)
  :name "2cos (problem 3.3.5)"
  (- (cos (+ x eps)) (cos x)))