Average Error: 59.8 → 0.4
Time: 39.2s
Precision: 64
Internal Precision: 2368
\[\frac{1}{x} - \frac{1}{\tan x}\]
\[\left(\frac{2}{945} \cdot {x}^{5} + \frac{\frac{-1}{3}}{\frac{-1}{x}}\right) + \left(\frac{1}{45} \cdot x\right) \cdot \left(x \cdot x\right)\]

Error

Bits error versus x

Target

Original59.8
Target0.1
Herbie0.4
\[\begin{array}{l} \mathbf{if}\;\left|x\right| \lt 0.026:\\ \;\;\;\;\frac{x}{3} \cdot \left(1 + \frac{x \cdot x}{15}\right)\\ \mathbf{else}:\\ \;\;\;\;\frac{1}{x} - \frac{1}{\tan x}\\ \end{array}\]

Derivation

  1. Initial program 59.8

    \[\frac{1}{x} - \frac{1}{\tan x}\]
  2. Taylor expanded around 0 0.3

    \[\leadsto \color{blue}{\frac{1}{45} \cdot {x}^{3} + \left(\frac{2}{945} \cdot {x}^{5} + \frac{1}{3} \cdot x\right)}\]
  3. Using strategy rm
  4. Applied add-cube-cbrt1.5

    \[\leadsto \frac{1}{45} \cdot {x}^{3} + \left(\frac{2}{945} \cdot {x}^{5} + \color{blue}{\left(\sqrt[3]{\frac{1}{3} \cdot x} \cdot \sqrt[3]{\frac{1}{3} \cdot x}\right) \cdot \sqrt[3]{\frac{1}{3} \cdot x}}\right)\]
  5. Taylor expanded around inf 34.6

    \[\leadsto \frac{1}{45} \cdot {x}^{3} + \left(\frac{2}{945} \cdot {x}^{5} + \left(\sqrt[3]{\frac{1}{3} \cdot x} \cdot \sqrt[3]{\frac{1}{3} \cdot x}\right) \cdot \color{blue}{e^{\frac{1}{3} \cdot \left(\log \frac{1}{3} - \log \left(\frac{1}{x}\right)\right)}}\right)\]
  6. Applied simplify1.5

    \[\leadsto \color{blue}{{\left(\sqrt[3]{\frac{1}{3} \cdot x}\right)}^{3} + \left(\left(x \cdot x\right) \cdot \left(x \cdot \frac{1}{45}\right) + \frac{2}{945} \cdot {x}^{5}\right)}\]
  7. Taylor expanded around -inf 62.9

    \[\leadsto \color{blue}{e^{\log \frac{-1}{3} - \log \left(\frac{-1}{x}\right)}} + \left(\left(x \cdot x\right) \cdot \left(x \cdot \frac{1}{45}\right) + \frac{2}{945} \cdot {x}^{5}\right)\]
  8. Applied simplify0.4

    \[\leadsto \color{blue}{\left(\frac{2}{945} \cdot {x}^{5} + \frac{\frac{-1}{3}}{\frac{-1}{x}}\right) + \left(\frac{1}{45} \cdot x\right) \cdot \left(x \cdot x\right)}\]

Runtime

Time bar (total: 39.2s)Debug logProfile

herbie shell --seed '#(1071246582 2318319007 2683472949 3810440501 3233274817 2724848749)' 
(FPCore (x)
  :name "invcot (example 3.9)"
  :pre (and (< -0.026 x) (< x 0.026))

  :herbie-target
  (if (< (fabs x) 0.026) (* (/ x 3) (+ 1 (/ (* x x) 15))) (- (/ 1 x) (/ 1 (tan x))))

  (- (/ 1 x) (/ 1 (tan x))))