Average Error: 37.2 → 0.4
Time: 47.0s
Precision: 64
Internal Precision: 128
\[\sin \left(x + \varepsilon\right) - \sin x\]
\[(\left(\cos x\right) \cdot \left(\sin \varepsilon\right) + \left(\sin x \cdot \log \left(e^{\cos \varepsilon - 1}\right)\right))_*\]

Error

Bits error versus x

Bits error versus eps

Target

Original37.2
Target15.6
Herbie0.4
\[2 \cdot \left(\cos \left(x + \frac{\varepsilon}{2}\right) \cdot \sin \left(\frac{\varepsilon}{2}\right)\right)\]

Derivation

  1. Initial program 37.2

    \[\sin \left(x + \varepsilon\right) - \sin x\]
  2. Using strategy rm
  3. Applied +-commutative37.2

    \[\leadsto \sin \color{blue}{\left(\varepsilon + x\right)} - \sin x\]
  4. Applied sin-sum21.3

    \[\leadsto \color{blue}{\left(\sin \varepsilon \cdot \cos x + \cos \varepsilon \cdot \sin x\right)} - \sin x\]
  5. Applied associate--l+0.4

    \[\leadsto \color{blue}{\sin \varepsilon \cdot \cos x + \left(\cos \varepsilon \cdot \sin x - \sin x\right)}\]
  6. Using strategy rm
  7. Applied *-commutative0.4

    \[\leadsto \color{blue}{\cos x \cdot \sin \varepsilon} + \left(\cos \varepsilon \cdot \sin x - \sin x\right)\]
  8. Applied fma-def0.4

    \[\leadsto \color{blue}{(\left(\cos x\right) \cdot \left(\sin \varepsilon\right) + \left(\cos \varepsilon \cdot \sin x - \sin x\right))_*}\]
  9. Using strategy rm
  10. Applied *-un-lft-identity0.4

    \[\leadsto (\left(\cos x\right) \cdot \left(\sin \varepsilon\right) + \left(\cos \varepsilon \cdot \sin x - \color{blue}{1 \cdot \sin x}\right))_*\]
  11. Applied distribute-rgt-out--0.4

    \[\leadsto (\left(\cos x\right) \cdot \left(\sin \varepsilon\right) + \color{blue}{\left(\sin x \cdot \left(\cos \varepsilon - 1\right)\right)})_*\]
  12. Using strategy rm
  13. Applied add-log-exp0.4

    \[\leadsto (\left(\cos x\right) \cdot \left(\sin \varepsilon\right) + \left(\sin x \cdot \color{blue}{\log \left(e^{\cos \varepsilon - 1}\right)}\right))_*\]
  14. Final simplification0.4

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

Reproduce

herbie shell --seed 2019088 +o rules:numerics
(FPCore (x eps)
  :name "2sin (example 3.3)"

  :herbie-target
  (* 2 (* (cos (+ x (/ eps 2))) (sin (/ eps 2))))

  (- (sin (+ x eps)) (sin x)))