Average Error: 6.0 → 0.6
Time: 21.1s
Precision: 64
\[x + \frac{e^{y \cdot \log \left(\frac{y}{z + y}\right)}}{y}\]
\[\begin{array}{l} \mathbf{if}\;y \le -6.13689162563550475538429628460746343967 \cdot 10^{60}:\\ \;\;\;\;\mathsf{fma}\left(\frac{\sqrt{e^{-z}}}{\sqrt[3]{y} \cdot \sqrt[3]{y}}, \frac{\sqrt{e^{-z}}}{\sqrt[3]{y}}, x\right)\\ \mathbf{else}:\\ \;\;\;\;x + \frac{e^{\left(2 \cdot \log \left(\frac{\sqrt[3]{y}}{\sqrt[3]{z + y}}\right)\right) \cdot y + y \cdot \log \left(\frac{\sqrt[3]{y}}{\sqrt[3]{z + y}}\right)}}{y}\\ \end{array}\]
x + \frac{e^{y \cdot \log \left(\frac{y}{z + y}\right)}}{y}
\begin{array}{l}
\mathbf{if}\;y \le -6.13689162563550475538429628460746343967 \cdot 10^{60}:\\
\;\;\;\;\mathsf{fma}\left(\frac{\sqrt{e^{-z}}}{\sqrt[3]{y} \cdot \sqrt[3]{y}}, \frac{\sqrt{e^{-z}}}{\sqrt[3]{y}}, x\right)\\

\mathbf{else}:\\
\;\;\;\;x + \frac{e^{\left(2 \cdot \log \left(\frac{\sqrt[3]{y}}{\sqrt[3]{z + y}}\right)\right) \cdot y + y \cdot \log \left(\frac{\sqrt[3]{y}}{\sqrt[3]{z + y}}\right)}}{y}\\

\end{array}
double f(double x, double y, double z) {
        double r247358 = x;
        double r247359 = y;
        double r247360 = z;
        double r247361 = r247360 + r247359;
        double r247362 = r247359 / r247361;
        double r247363 = log(r247362);
        double r247364 = r247359 * r247363;
        double r247365 = exp(r247364);
        double r247366 = r247365 / r247359;
        double r247367 = r247358 + r247366;
        return r247367;
}

double f(double x, double y, double z) {
        double r247368 = y;
        double r247369 = -6.136891625635505e+60;
        bool r247370 = r247368 <= r247369;
        double r247371 = z;
        double r247372 = -r247371;
        double r247373 = exp(r247372);
        double r247374 = sqrt(r247373);
        double r247375 = cbrt(r247368);
        double r247376 = r247375 * r247375;
        double r247377 = r247374 / r247376;
        double r247378 = r247374 / r247375;
        double r247379 = x;
        double r247380 = fma(r247377, r247378, r247379);
        double r247381 = 2.0;
        double r247382 = r247371 + r247368;
        double r247383 = cbrt(r247382);
        double r247384 = r247375 / r247383;
        double r247385 = log(r247384);
        double r247386 = r247381 * r247385;
        double r247387 = r247386 * r247368;
        double r247388 = r247368 * r247385;
        double r247389 = r247387 + r247388;
        double r247390 = exp(r247389);
        double r247391 = r247390 / r247368;
        double r247392 = r247379 + r247391;
        double r247393 = r247370 ? r247380 : r247392;
        return r247393;
}

Error

Bits error versus x

Bits error versus y

Bits error versus z

Target

Original6.0
Target1.0
Herbie0.6
\[\begin{array}{l} \mathbf{if}\;\frac{y}{z + y} \lt 7.115415759790762719541517221498726780517 \cdot 10^{-315}:\\ \;\;\;\;x + \frac{e^{\frac{-1}{z}}}{y}\\ \mathbf{else}:\\ \;\;\;\;x + \frac{e^{\log \left({\left(\frac{y}{y + z}\right)}^{y}\right)}}{y}\\ \end{array}\]

Derivation

  1. Split input into 2 regimes
  2. if y < -6.136891625635505e+60

    1. Initial program 2.4

      \[x + \frac{e^{y \cdot \log \left(\frac{y}{z + y}\right)}}{y}\]
    2. Taylor expanded around inf 0.1

      \[\leadsto \color{blue}{x + \frac{e^{-1 \cdot z}}{y}}\]
    3. Simplified0.1

      \[\leadsto \color{blue}{\frac{e^{-z}}{y} + x}\]
    4. Using strategy rm
    5. Applied add-cube-cbrt0.3

      \[\leadsto \frac{e^{-z}}{\color{blue}{\left(\sqrt[3]{y} \cdot \sqrt[3]{y}\right) \cdot \sqrt[3]{y}}} + x\]
    6. Applied add-sqr-sqrt0.3

      \[\leadsto \frac{\color{blue}{\sqrt{e^{-z}} \cdot \sqrt{e^{-z}}}}{\left(\sqrt[3]{y} \cdot \sqrt[3]{y}\right) \cdot \sqrt[3]{y}} + x\]
    7. Applied times-frac0.3

      \[\leadsto \color{blue}{\frac{\sqrt{e^{-z}}}{\sqrt[3]{y} \cdot \sqrt[3]{y}} \cdot \frac{\sqrt{e^{-z}}}{\sqrt[3]{y}}} + x\]
    8. Applied fma-def0.3

      \[\leadsto \color{blue}{\mathsf{fma}\left(\frac{\sqrt{e^{-z}}}{\sqrt[3]{y} \cdot \sqrt[3]{y}}, \frac{\sqrt{e^{-z}}}{\sqrt[3]{y}}, x\right)}\]

    if -6.136891625635505e+60 < y

    1. Initial program 6.9

      \[x + \frac{e^{y \cdot \log \left(\frac{y}{z + y}\right)}}{y}\]
    2. Using strategy rm
    3. Applied add-cube-cbrt15.0

      \[\leadsto x + \frac{e^{y \cdot \log \left(\frac{y}{\color{blue}{\left(\sqrt[3]{z + y} \cdot \sqrt[3]{z + y}\right) \cdot \sqrt[3]{z + y}}}\right)}}{y}\]
    4. Applied add-cube-cbrt6.9

      \[\leadsto x + \frac{e^{y \cdot \log \left(\frac{\color{blue}{\left(\sqrt[3]{y} \cdot \sqrt[3]{y}\right) \cdot \sqrt[3]{y}}}{\left(\sqrt[3]{z + y} \cdot \sqrt[3]{z + y}\right) \cdot \sqrt[3]{z + y}}\right)}}{y}\]
    5. Applied times-frac6.9

      \[\leadsto x + \frac{e^{y \cdot \log \color{blue}{\left(\frac{\sqrt[3]{y} \cdot \sqrt[3]{y}}{\sqrt[3]{z + y} \cdot \sqrt[3]{z + y}} \cdot \frac{\sqrt[3]{y}}{\sqrt[3]{z + y}}\right)}}}{y}\]
    6. Applied log-prod1.9

      \[\leadsto x + \frac{e^{y \cdot \color{blue}{\left(\log \left(\frac{\sqrt[3]{y} \cdot \sqrt[3]{y}}{\sqrt[3]{z + y} \cdot \sqrt[3]{z + y}}\right) + \log \left(\frac{\sqrt[3]{y}}{\sqrt[3]{z + y}}\right)\right)}}}{y}\]
    7. Applied distribute-lft-in1.9

      \[\leadsto x + \frac{e^{\color{blue}{y \cdot \log \left(\frac{\sqrt[3]{y} \cdot \sqrt[3]{y}}{\sqrt[3]{z + y} \cdot \sqrt[3]{z + y}}\right) + y \cdot \log \left(\frac{\sqrt[3]{y}}{\sqrt[3]{z + y}}\right)}}}{y}\]
    8. Simplified0.7

      \[\leadsto x + \frac{e^{\color{blue}{\left(2 \cdot \log \left(\frac{\sqrt[3]{y}}{\sqrt[3]{z + y}}\right)\right) \cdot y} + y \cdot \log \left(\frac{\sqrt[3]{y}}{\sqrt[3]{z + y}}\right)}}{y}\]
  3. Recombined 2 regimes into one program.
  4. Final simplification0.6

    \[\leadsto \begin{array}{l} \mathbf{if}\;y \le -6.13689162563550475538429628460746343967 \cdot 10^{60}:\\ \;\;\;\;\mathsf{fma}\left(\frac{\sqrt{e^{-z}}}{\sqrt[3]{y} \cdot \sqrt[3]{y}}, \frac{\sqrt{e^{-z}}}{\sqrt[3]{y}}, x\right)\\ \mathbf{else}:\\ \;\;\;\;x + \frac{e^{\left(2 \cdot \log \left(\frac{\sqrt[3]{y}}{\sqrt[3]{z + y}}\right)\right) \cdot y + y \cdot \log \left(\frac{\sqrt[3]{y}}{\sqrt[3]{z + y}}\right)}}{y}\\ \end{array}\]

Reproduce

herbie shell --seed 2019326 +o rules:numerics
(FPCore (x y z)
  :name "Numeric.SpecFunctions:invIncompleteBetaWorker from math-functions-0.1.5.2, G"
  :precision binary64

  :herbie-target
  (if (< (/ y (+ z y)) 7.1154157597908e-315) (+ x (/ (exp (/ -1 z)) y)) (+ x (/ (exp (log (pow (/ y (+ y z)) y))) y)))

  (+ x (/ (exp (* y (log (/ y (+ z y))))) y)))