Average Error: 37.1 → 13.7
Time: 1.5m
Precision: 64
Internal Precision: 2432
\[\tan \left(x + \varepsilon\right) - \tan x\]
\[\begin{array}{l} \mathbf{if}\;(\left(x \cdot \varepsilon\right) \cdot \left((\left(x \cdot \varepsilon\right) \cdot \varepsilon + \varepsilon)_*\right) + \varepsilon)_* \le -3.1068469719484584 \cdot 10^{-28}:\\ \;\;\;\;\frac{(\left(\cos x\right) \cdot \left(\tan x + \tan \varepsilon\right) + \left((\left(\sin x\right) \cdot \left(\tan \varepsilon \cdot \tan x\right) + \left(-\sin x\right))_*\right))_*}{(\left(\tan \varepsilon \cdot \cos x\right) \cdot \left(-\tan x\right) + \left(\cos x\right))_*}\\ \mathbf{if}\;(\left(x \cdot \varepsilon\right) \cdot \left((\left(x \cdot \varepsilon\right) \cdot \varepsilon + \varepsilon)_*\right) + \varepsilon)_* \le 5.858083040047354 \cdot 10^{-17}:\\ \;\;\;\;(\left(x \cdot \varepsilon\right) \cdot \left((\left(x \cdot \varepsilon\right) \cdot \varepsilon + \varepsilon)_*\right) + \varepsilon)_*\\ \mathbf{else}:\\ \;\;\;\;\frac{(\left(\cos x\right) \cdot \left(\tan x + \tan \varepsilon\right) + \left((\left(\sin x\right) \cdot \left(\tan \varepsilon \cdot \tan x\right) + \left(-\sin x\right))_*\right))_*}{(\left(\tan \varepsilon \cdot \cos x\right) \cdot \left(-\tan x\right) + \left(\cos x\right))_*}\\ \end{array}\]

Error

Bits error versus x

Bits error versus eps

Target

Original37.1
Target15.6
Herbie13.7
\[\frac{\sin \varepsilon}{\cos x \cdot \cos \left(x + \varepsilon\right)}\]

Derivation

  1. Split input into 2 regimes
  2. if (fma (* x eps) (fma (* x eps) eps eps) eps) < -3.1068469719484584e-28 or 5.858083040047354e-17 < (fma (* x eps) (fma (* x eps) eps eps) eps)

    1. Initial program 34.3

      \[\tan \left(x + \varepsilon\right) - \tan x\]
    2. Using strategy rm
    3. Applied tan-sum8.6

      \[\leadsto \color{blue}{\frac{\tan x + \tan \varepsilon}{1 - \tan x \cdot \tan \varepsilon}} - \tan x\]
    4. Using strategy rm
    5. Applied add-log-exp8.7

      \[\leadsto \frac{\tan x + \tan \varepsilon}{1 - \color{blue}{\log \left(e^{\tan x \cdot \tan \varepsilon}\right)}} - \tan x\]
    6. Using strategy rm
    7. Applied tan-quot8.7

      \[\leadsto \frac{\tan x + \tan \varepsilon}{1 - \log \left(e^{\tan x \cdot \tan \varepsilon}\right)} - \color{blue}{\frac{\sin x}{\cos x}}\]
    8. Applied frac-sub8.8

      \[\leadsto \color{blue}{\frac{\left(\tan x + \tan \varepsilon\right) \cdot \cos x - \left(1 - \log \left(e^{\tan x \cdot \tan \varepsilon}\right)\right) \cdot \sin x}{\left(1 - \log \left(e^{\tan x \cdot \tan \varepsilon}\right)\right) \cdot \cos x}}\]
    9. Applied simplify8.7

      \[\leadsto \frac{\color{blue}{(\left(\cos x\right) \cdot \left(\tan x + \tan \varepsilon\right) + \left((\left(\sin x\right) \cdot \left(\tan \varepsilon \cdot \tan x\right) + \left(-\sin x\right))_*\right))_*}}{\left(1 - \log \left(e^{\tan x \cdot \tan \varepsilon}\right)\right) \cdot \cos x}\]
    10. Applied simplify8.6

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

    if -3.1068469719484584e-28 < (fma (* x eps) (fma (* x eps) eps eps) eps) < 5.858083040047354e-17

    1. Initial program 41.4

      \[\tan \left(x + \varepsilon\right) - \tan x\]
    2. Taylor expanded around 0 23.0

      \[\leadsto \color{blue}{\varepsilon + \left({\varepsilon}^{3} \cdot {x}^{2} + {\varepsilon}^{2} \cdot x\right)}\]
    3. Applied simplify21.9

      \[\leadsto \color{blue}{(\left(x \cdot \varepsilon\right) \cdot \left((\left(x \cdot \varepsilon\right) \cdot \varepsilon + \varepsilon)_*\right) + \varepsilon)_*}\]
  3. Recombined 2 regimes into one program.

Runtime

Time bar (total: 1.5m)Debug logProfile

herbie shell --seed '#(1070833653 108281690 3330367898 3632331308 3494323072 43156186)' +o rules:numerics
(FPCore (x eps)
  :name "2tan (problem 3.3.2)"

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

  (- (tan (+ x eps)) (tan x)))