Average Error: 53.1 → 0.2
Time: 17.6s
Precision: 64
\[\log \left(x + \sqrt{x \cdot x + 1}\right)\]
\[\begin{array}{l} \mathbf{if}\;x \le -1.019640201583560834563968455768190324306:\\ \;\;\;\;\log \left(\frac{0.125}{\left(x \cdot x\right) \cdot x} - \left(\frac{0.0625}{{x}^{5}} + \frac{0.5}{x}\right)\right)\\ \mathbf{elif}\;x \le 0.9010700472866574051167276593332644551992:\\ \;\;\;\;\left(\log \left(\sqrt{1}\right) + \frac{x}{\sqrt{1}}\right) - \frac{\frac{1}{6}}{1} \cdot \frac{\left(x \cdot x\right) \cdot x}{\sqrt{1}}\\ \mathbf{else}:\\ \;\;\;\;\log \left(\left(\left(x + \frac{0.5}{x}\right) - \frac{0.125}{\left(x \cdot x\right) \cdot x}\right) + x\right)\\ \end{array}\]
\log \left(x + \sqrt{x \cdot x + 1}\right)
\begin{array}{l}
\mathbf{if}\;x \le -1.019640201583560834563968455768190324306:\\
\;\;\;\;\log \left(\frac{0.125}{\left(x \cdot x\right) \cdot x} - \left(\frac{0.0625}{{x}^{5}} + \frac{0.5}{x}\right)\right)\\

\mathbf{elif}\;x \le 0.9010700472866574051167276593332644551992:\\
\;\;\;\;\left(\log \left(\sqrt{1}\right) + \frac{x}{\sqrt{1}}\right) - \frac{\frac{1}{6}}{1} \cdot \frac{\left(x \cdot x\right) \cdot x}{\sqrt{1}}\\

\mathbf{else}:\\
\;\;\;\;\log \left(\left(\left(x + \frac{0.5}{x}\right) - \frac{0.125}{\left(x \cdot x\right) \cdot x}\right) + x\right)\\

\end{array}
double f(double x) {
        double r6965366 = x;
        double r6965367 = r6965366 * r6965366;
        double r6965368 = 1.0;
        double r6965369 = r6965367 + r6965368;
        double r6965370 = sqrt(r6965369);
        double r6965371 = r6965366 + r6965370;
        double r6965372 = log(r6965371);
        return r6965372;
}

double f(double x) {
        double r6965373 = x;
        double r6965374 = -1.0196402015835608;
        bool r6965375 = r6965373 <= r6965374;
        double r6965376 = 0.125;
        double r6965377 = r6965373 * r6965373;
        double r6965378 = r6965377 * r6965373;
        double r6965379 = r6965376 / r6965378;
        double r6965380 = 0.0625;
        double r6965381 = 5.0;
        double r6965382 = pow(r6965373, r6965381);
        double r6965383 = r6965380 / r6965382;
        double r6965384 = 0.5;
        double r6965385 = r6965384 / r6965373;
        double r6965386 = r6965383 + r6965385;
        double r6965387 = r6965379 - r6965386;
        double r6965388 = log(r6965387);
        double r6965389 = 0.9010700472866574;
        bool r6965390 = r6965373 <= r6965389;
        double r6965391 = 1.0;
        double r6965392 = sqrt(r6965391);
        double r6965393 = log(r6965392);
        double r6965394 = r6965373 / r6965392;
        double r6965395 = r6965393 + r6965394;
        double r6965396 = 0.16666666666666666;
        double r6965397 = r6965396 / r6965391;
        double r6965398 = r6965378 / r6965392;
        double r6965399 = r6965397 * r6965398;
        double r6965400 = r6965395 - r6965399;
        double r6965401 = r6965373 + r6965385;
        double r6965402 = r6965401 - r6965379;
        double r6965403 = r6965402 + r6965373;
        double r6965404 = log(r6965403);
        double r6965405 = r6965390 ? r6965400 : r6965404;
        double r6965406 = r6965375 ? r6965388 : r6965405;
        return r6965406;
}

Error

Bits error versus x

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Target

Original53.1
Target45.5
Herbie0.2
\[\begin{array}{l} \mathbf{if}\;x \lt 0.0:\\ \;\;\;\;\log \left(\frac{-1}{x - \sqrt{x \cdot x + 1}}\right)\\ \mathbf{else}:\\ \;\;\;\;\log \left(x + \sqrt{x \cdot x + 1}\right)\\ \end{array}\]

Derivation

  1. Split input into 3 regimes
  2. if x < -1.0196402015835608

    1. Initial program 62.8

      \[\log \left(x + \sqrt{x \cdot x + 1}\right)\]
    2. Taylor expanded around -inf 0.2

      \[\leadsto \log \color{blue}{\left(0.125 \cdot \frac{1}{{x}^{3}} - \left(0.0625 \cdot \frac{1}{{x}^{5}} + 0.5 \cdot \frac{1}{x}\right)\right)}\]
    3. Simplified0.2

      \[\leadsto \log \color{blue}{\left(\frac{0.125}{x \cdot \left(x \cdot x\right)} - \left(\frac{0.5}{x} + \frac{0.0625}{{x}^{5}}\right)\right)}\]

    if -1.0196402015835608 < x < 0.9010700472866574

    1. Initial program 58.6

      \[\log \left(x + \sqrt{x \cdot x + 1}\right)\]
    2. Taylor expanded around 0 0.2

      \[\leadsto \color{blue}{\left(\frac{x}{\sqrt{1}} + \log \left(\sqrt{1}\right)\right) - \frac{1}{6} \cdot \frac{{x}^{3}}{{\left(\sqrt{1}\right)}^{3}}}\]
    3. Simplified0.2

      \[\leadsto \color{blue}{\left(\log \left(\sqrt{1}\right) + \frac{x}{\sqrt{1}}\right) - \frac{x \cdot \left(x \cdot x\right)}{\sqrt{1}} \cdot \frac{\frac{1}{6}}{1}}\]

    if 0.9010700472866574 < x

    1. Initial program 32.0

      \[\log \left(x + \sqrt{x \cdot x + 1}\right)\]
    2. Taylor expanded around inf 0.2

      \[\leadsto \log \left(x + \color{blue}{\left(\left(x + 0.5 \cdot \frac{1}{x}\right) - 0.125 \cdot \frac{1}{{x}^{3}}\right)}\right)\]
    3. Simplified0.2

      \[\leadsto \log \left(x + \color{blue}{\left(\left(x + \frac{0.5}{x}\right) - \frac{0.125}{x \cdot \left(x \cdot x\right)}\right)}\right)\]
  3. Recombined 3 regimes into one program.
  4. Final simplification0.2

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \le -1.019640201583560834563968455768190324306:\\ \;\;\;\;\log \left(\frac{0.125}{\left(x \cdot x\right) \cdot x} - \left(\frac{0.0625}{{x}^{5}} + \frac{0.5}{x}\right)\right)\\ \mathbf{elif}\;x \le 0.9010700472866574051167276593332644551992:\\ \;\;\;\;\left(\log \left(\sqrt{1}\right) + \frac{x}{\sqrt{1}}\right) - \frac{\frac{1}{6}}{1} \cdot \frac{\left(x \cdot x\right) \cdot x}{\sqrt{1}}\\ \mathbf{else}:\\ \;\;\;\;\log \left(\left(\left(x + \frac{0.5}{x}\right) - \frac{0.125}{\left(x \cdot x\right) \cdot x}\right) + x\right)\\ \end{array}\]

Reproduce

herbie shell --seed 2019192 
(FPCore (x)
  :name "Hyperbolic arcsine"

  :herbie-target
  (if (< x 0.0) (log (/ -1.0 (- x (sqrt (+ (* x x) 1.0))))) (log (+ x (sqrt (+ (* x x) 1.0)))))

  (log (+ x (sqrt (+ (* x x) 1.0)))))