Average Error: 30.3 → 0.6
Time: 6.6s
Precision: 64
\[\frac{1 - \cos x}{\sin x}\]
\[\begin{array}{l} \mathbf{if}\;\frac{1 - \cos x}{\sin x} \le -9.955579397094595477807343897325154102873 \cdot 10^{-4}:\\ \;\;\;\;\frac{{1}^{3} - {\left(\cos x\right)}^{3}}{\left(\cos x \cdot \left(\cos x + 1\right) + 1 \cdot 1\right) \cdot \sin x}\\ \mathbf{elif}\;\frac{1 - \cos x}{\sin x} \le 6.585706534220822007288757837795145633208 \cdot 10^{-6}:\\ \;\;\;\;\left(\frac{1}{24} \cdot {x}^{3} + \frac{1}{240} \cdot {x}^{5}\right) + \frac{1}{2} \cdot x\\ \mathbf{else}:\\ \;\;\;\;\frac{1}{\sin x} \cdot \left(1 - \cos x\right)\\ \end{array}\]
\frac{1 - \cos x}{\sin x}
\begin{array}{l}
\mathbf{if}\;\frac{1 - \cos x}{\sin x} \le -9.955579397094595477807343897325154102873 \cdot 10^{-4}:\\
\;\;\;\;\frac{{1}^{3} - {\left(\cos x\right)}^{3}}{\left(\cos x \cdot \left(\cos x + 1\right) + 1 \cdot 1\right) \cdot \sin x}\\

\mathbf{elif}\;\frac{1 - \cos x}{\sin x} \le 6.585706534220822007288757837795145633208 \cdot 10^{-6}:\\
\;\;\;\;\left(\frac{1}{24} \cdot {x}^{3} + \frac{1}{240} \cdot {x}^{5}\right) + \frac{1}{2} \cdot x\\

\mathbf{else}:\\
\;\;\;\;\frac{1}{\sin x} \cdot \left(1 - \cos x\right)\\

\end{array}
double f(double x) {
        double r161567 = 1.0;
        double r161568 = x;
        double r161569 = cos(r161568);
        double r161570 = r161567 - r161569;
        double r161571 = sin(r161568);
        double r161572 = r161570 / r161571;
        return r161572;
}

double f(double x) {
        double r161573 = 1.0;
        double r161574 = x;
        double r161575 = cos(r161574);
        double r161576 = r161573 - r161575;
        double r161577 = sin(r161574);
        double r161578 = r161576 / r161577;
        double r161579 = -0.0009955579397094595;
        bool r161580 = r161578 <= r161579;
        double r161581 = 3.0;
        double r161582 = pow(r161573, r161581);
        double r161583 = pow(r161575, r161581);
        double r161584 = r161582 - r161583;
        double r161585 = r161575 + r161573;
        double r161586 = r161575 * r161585;
        double r161587 = r161573 * r161573;
        double r161588 = r161586 + r161587;
        double r161589 = r161588 * r161577;
        double r161590 = r161584 / r161589;
        double r161591 = 6.585706534220822e-06;
        bool r161592 = r161578 <= r161591;
        double r161593 = 0.041666666666666664;
        double r161594 = pow(r161574, r161581);
        double r161595 = r161593 * r161594;
        double r161596 = 0.004166666666666667;
        double r161597 = 5.0;
        double r161598 = pow(r161574, r161597);
        double r161599 = r161596 * r161598;
        double r161600 = r161595 + r161599;
        double r161601 = 0.5;
        double r161602 = r161601 * r161574;
        double r161603 = r161600 + r161602;
        double r161604 = 1.0;
        double r161605 = r161604 / r161577;
        double r161606 = r161605 * r161576;
        double r161607 = r161592 ? r161603 : r161606;
        double r161608 = r161580 ? r161590 : r161607;
        return r161608;
}

Error

Bits error versus x

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Target

Original30.3
Target0.0
Herbie0.6
\[\tan \left(\frac{x}{2}\right)\]

Derivation

  1. Split input into 3 regimes
  2. if (/ (- 1.0 (cos x)) (sin x)) < -0.0009955579397094595

    1. Initial program 0.9

      \[\frac{1 - \cos x}{\sin x}\]
    2. Using strategy rm
    3. Applied flip3--1.0

      \[\leadsto \frac{\color{blue}{\frac{{1}^{3} - {\left(\cos x\right)}^{3}}{1 \cdot 1 + \left(\cos x \cdot \cos x + 1 \cdot \cos x\right)}}}{\sin x}\]
    4. Applied associate-/l/1.0

      \[\leadsto \color{blue}{\frac{{1}^{3} - {\left(\cos x\right)}^{3}}{\sin x \cdot \left(1 \cdot 1 + \left(\cos x \cdot \cos x + 1 \cdot \cos x\right)\right)}}\]
    5. Simplified1.0

      \[\leadsto \frac{{1}^{3} - {\left(\cos x\right)}^{3}}{\color{blue}{\left(\cos x \cdot \left(\cos x + 1\right) + 1 \cdot 1\right) \cdot \sin x}}\]

    if -0.0009955579397094595 < (/ (- 1.0 (cos x)) (sin x)) < 6.585706534220822e-06

    1. Initial program 60.3

      \[\frac{1 - \cos x}{\sin x}\]
    2. Taylor expanded around 0 0.0

      \[\leadsto \color{blue}{\frac{1}{24} \cdot {x}^{3} + \left(\frac{1}{240} \cdot {x}^{5} + \frac{1}{2} \cdot x\right)}\]
    3. Using strategy rm
    4. Applied associate-+r+0.0

      \[\leadsto \color{blue}{\left(\frac{1}{24} \cdot {x}^{3} + \frac{1}{240} \cdot {x}^{5}\right) + \frac{1}{2} \cdot x}\]

    if 6.585706534220822e-06 < (/ (- 1.0 (cos x)) (sin x))

    1. Initial program 1.2

      \[\frac{1 - \cos x}{\sin x}\]
    2. Using strategy rm
    3. Applied clear-num1.2

      \[\leadsto \color{blue}{\frac{1}{\frac{\sin x}{1 - \cos x}}}\]
    4. Using strategy rm
    5. Applied div-inv1.3

      \[\leadsto \frac{1}{\color{blue}{\sin x \cdot \frac{1}{1 - \cos x}}}\]
    6. Applied add-cube-cbrt1.3

      \[\leadsto \frac{\color{blue}{\left(\sqrt[3]{1} \cdot \sqrt[3]{1}\right) \cdot \sqrt[3]{1}}}{\sin x \cdot \frac{1}{1 - \cos x}}\]
    7. Applied times-frac1.3

      \[\leadsto \color{blue}{\frac{\sqrt[3]{1} \cdot \sqrt[3]{1}}{\sin x} \cdot \frac{\sqrt[3]{1}}{\frac{1}{1 - \cos x}}}\]
    8. Simplified1.3

      \[\leadsto \color{blue}{\frac{1}{\sin x}} \cdot \frac{\sqrt[3]{1}}{\frac{1}{1 - \cos x}}\]
    9. Simplified1.2

      \[\leadsto \frac{1}{\sin x} \cdot \color{blue}{\left(1 - \cos x\right)}\]
  3. Recombined 3 regimes into one program.
  4. Final simplification0.6

    \[\leadsto \begin{array}{l} \mathbf{if}\;\frac{1 - \cos x}{\sin x} \le -9.955579397094595477807343897325154102873 \cdot 10^{-4}:\\ \;\;\;\;\frac{{1}^{3} - {\left(\cos x\right)}^{3}}{\left(\cos x \cdot \left(\cos x + 1\right) + 1 \cdot 1\right) \cdot \sin x}\\ \mathbf{elif}\;\frac{1 - \cos x}{\sin x} \le 6.585706534220822007288757837795145633208 \cdot 10^{-6}:\\ \;\;\;\;\left(\frac{1}{24} \cdot {x}^{3} + \frac{1}{240} \cdot {x}^{5}\right) + \frac{1}{2} \cdot x\\ \mathbf{else}:\\ \;\;\;\;\frac{1}{\sin x} \cdot \left(1 - \cos x\right)\\ \end{array}\]

Reproduce

herbie shell --seed 2019356 
(FPCore (x)
  :name "tanhf (example 3.4)"
  :precision binary64
  :herbie-expected 2

  :herbie-target
  (tan (/ x 2))

  (/ (- 1 (cos x)) (sin x)))