Average Error: 9.8 → 0.1
Time: 18.1s
Precision: 64
\[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}\]
\[\begin{array}{l} \mathbf{if}\;x \le -117.2709864418915515216212952509522438049:\\ \;\;\;\;\frac{\frac{\frac{2}{x}}{x}}{x} + \left(\frac{2}{{x}^{7}} + \frac{2}{{x}^{5}}\right)\\ \mathbf{elif}\;x \le 115.5593852642430903188142110593616962433:\\ \;\;\;\;\frac{1 \cdot x - \left(x + 1\right) \cdot 2}{\left(x + 1\right) \cdot x} + \frac{1}{x - 1}\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{2}{x}}{x \cdot x} + \left(\frac{2}{{x}^{7}} + \frac{2}{{x}^{5}}\right)\\ \end{array}\]
\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}
\begin{array}{l}
\mathbf{if}\;x \le -117.2709864418915515216212952509522438049:\\
\;\;\;\;\frac{\frac{\frac{2}{x}}{x}}{x} + \left(\frac{2}{{x}^{7}} + \frac{2}{{x}^{5}}\right)\\

\mathbf{elif}\;x \le 115.5593852642430903188142110593616962433:\\
\;\;\;\;\frac{1 \cdot x - \left(x + 1\right) \cdot 2}{\left(x + 1\right) \cdot x} + \frac{1}{x - 1}\\

\mathbf{else}:\\
\;\;\;\;\frac{\frac{2}{x}}{x \cdot x} + \left(\frac{2}{{x}^{7}} + \frac{2}{{x}^{5}}\right)\\

\end{array}
double f(double x) {
        double r101263 = 1.0;
        double r101264 = x;
        double r101265 = r101264 + r101263;
        double r101266 = r101263 / r101265;
        double r101267 = 2.0;
        double r101268 = r101267 / r101264;
        double r101269 = r101266 - r101268;
        double r101270 = r101264 - r101263;
        double r101271 = r101263 / r101270;
        double r101272 = r101269 + r101271;
        return r101272;
}

double f(double x) {
        double r101273 = x;
        double r101274 = -117.27098644189155;
        bool r101275 = r101273 <= r101274;
        double r101276 = 2.0;
        double r101277 = r101276 / r101273;
        double r101278 = r101277 / r101273;
        double r101279 = r101278 / r101273;
        double r101280 = 7.0;
        double r101281 = pow(r101273, r101280);
        double r101282 = r101276 / r101281;
        double r101283 = 5.0;
        double r101284 = pow(r101273, r101283);
        double r101285 = r101276 / r101284;
        double r101286 = r101282 + r101285;
        double r101287 = r101279 + r101286;
        double r101288 = 115.55938526424309;
        bool r101289 = r101273 <= r101288;
        double r101290 = 1.0;
        double r101291 = r101290 * r101273;
        double r101292 = r101273 + r101290;
        double r101293 = r101292 * r101276;
        double r101294 = r101291 - r101293;
        double r101295 = r101292 * r101273;
        double r101296 = r101294 / r101295;
        double r101297 = r101273 - r101290;
        double r101298 = r101290 / r101297;
        double r101299 = r101296 + r101298;
        double r101300 = r101273 * r101273;
        double r101301 = r101277 / r101300;
        double r101302 = r101301 + r101286;
        double r101303 = r101289 ? r101299 : r101302;
        double r101304 = r101275 ? r101287 : r101303;
        return r101304;
}

Error

Bits error versus x

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Target

Original9.8
Target0.2
Herbie0.1
\[\frac{2}{x \cdot \left(x \cdot x - 1\right)}\]

Derivation

  1. Split input into 3 regimes
  2. if x < -117.27098644189155

    1. Initial program 20.5

      \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}\]
    2. Using strategy rm
    3. Applied frac-sub52.6

      \[\leadsto \color{blue}{\frac{1 \cdot x - \left(x + 1\right) \cdot 2}{\left(x + 1\right) \cdot x}} + \frac{1}{x - 1}\]
    4. Taylor expanded around inf 0.3

      \[\leadsto \color{blue}{2 \cdot \frac{1}{{x}^{7}} + \left(2 \cdot \frac{1}{{x}^{5}} + 2 \cdot \frac{1}{{x}^{3}}\right)}\]
    5. Simplified0.3

      \[\leadsto \color{blue}{\frac{2}{{x}^{3}} + \left(\frac{2}{{x}^{7}} + \frac{2}{{x}^{5}}\right)}\]
    6. Using strategy rm
    7. Applied cube-mult0.4

      \[\leadsto \frac{2}{\color{blue}{x \cdot \left(x \cdot x\right)}} + \left(\frac{2}{{x}^{7}} + \frac{2}{{x}^{5}}\right)\]
    8. Applied associate-/r*0.1

      \[\leadsto \color{blue}{\frac{\frac{2}{x}}{x \cdot x}} + \left(\frac{2}{{x}^{7}} + \frac{2}{{x}^{5}}\right)\]
    9. Using strategy rm
    10. Applied associate-/r*0.1

      \[\leadsto \color{blue}{\frac{\frac{\frac{2}{x}}{x}}{x}} + \left(\frac{2}{{x}^{7}} + \frac{2}{{x}^{5}}\right)\]

    if -117.27098644189155 < x < 115.55938526424309

    1. Initial program 0.0

      \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}\]
    2. Using strategy rm
    3. Applied frac-sub0.0

      \[\leadsto \color{blue}{\frac{1 \cdot x - \left(x + 1\right) \cdot 2}{\left(x + 1\right) \cdot x}} + \frac{1}{x - 1}\]

    if 115.55938526424309 < x

    1. Initial program 18.8

      \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}\]
    2. Using strategy rm
    3. Applied frac-sub51.6

      \[\leadsto \color{blue}{\frac{1 \cdot x - \left(x + 1\right) \cdot 2}{\left(x + 1\right) \cdot x}} + \frac{1}{x - 1}\]
    4. Taylor expanded around inf 0.6

      \[\leadsto \color{blue}{2 \cdot \frac{1}{{x}^{7}} + \left(2 \cdot \frac{1}{{x}^{5}} + 2 \cdot \frac{1}{{x}^{3}}\right)}\]
    5. Simplified0.6

      \[\leadsto \color{blue}{\frac{2}{{x}^{3}} + \left(\frac{2}{{x}^{7}} + \frac{2}{{x}^{5}}\right)}\]
    6. Using strategy rm
    7. Applied cube-mult0.6

      \[\leadsto \frac{2}{\color{blue}{x \cdot \left(x \cdot x\right)}} + \left(\frac{2}{{x}^{7}} + \frac{2}{{x}^{5}}\right)\]
    8. Applied associate-/r*0.1

      \[\leadsto \color{blue}{\frac{\frac{2}{x}}{x \cdot x}} + \left(\frac{2}{{x}^{7}} + \frac{2}{{x}^{5}}\right)\]
  3. Recombined 3 regimes into one program.
  4. Final simplification0.1

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \le -117.2709864418915515216212952509522438049:\\ \;\;\;\;\frac{\frac{\frac{2}{x}}{x}}{x} + \left(\frac{2}{{x}^{7}} + \frac{2}{{x}^{5}}\right)\\ \mathbf{elif}\;x \le 115.5593852642430903188142110593616962433:\\ \;\;\;\;\frac{1 \cdot x - \left(x + 1\right) \cdot 2}{\left(x + 1\right) \cdot x} + \frac{1}{x - 1}\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{2}{x}}{x \cdot x} + \left(\frac{2}{{x}^{7}} + \frac{2}{{x}^{5}}\right)\\ \end{array}\]

Reproduce

herbie shell --seed 2019303 +o rules:numerics
(FPCore (x)
  :name "3frac (problem 3.3.3)"
  :precision binary64

  :herbie-target
  (/ 2 (* x (- (* x x) 1)))

  (+ (- (/ 1 (+ x 1)) (/ 2 x)) (/ 1 (- x 1))))