Average Error: 19.9 → 0.5
Time: 5.8s
Precision: 64
\[\frac{1}{\sqrt{x}} - \frac{1}{\sqrt{x + 1}}\]
↓
\[\frac{1 \cdot \sqrt[3]{{\left(\frac{1}{\sqrt{x + 1} + \sqrt{x}}\right)}^{3}}}{\sqrt{x} \cdot \sqrt{x + 1}}\]
\frac{1}{\sqrt{x}} - \frac{1}{\sqrt{x + 1}}
↓
\frac{1 \cdot \sqrt[3]{{\left(\frac{1}{\sqrt{x + 1} + \sqrt{x}}\right)}^{3}}}{\sqrt{x} \cdot \sqrt{x + 1}}
double f(double x) {
        double r143377 = 1.0;
        double r143378 = x;
        double r143379 = sqrt(r143378);
        double r143380 = r143377 / r143379;
        double r143381 = r143378 + r143377;
        double r143382 = sqrt(r143381);
        double r143383 = r143377 / r143382;
        double r143384 = r143380 - r143383;
        return r143384;
}
↓
double f(double x) {
        double r143385 = 1.0;
        double r143386 = x;
        double r143387 = r143386 + r143385;
        double r143388 = sqrt(r143387);
        double r143389 = sqrt(r143386);
        double r143390 = r143388 + r143389;
        double r143391 = r143385 / r143390;
        double r143392 = 3.0;
        double r143393 = pow(r143391, r143392);
        double r143394 = cbrt(r143393);
        double r143395 = r143385 * r143394;
        double r143396 = r143389 * r143388;
        double r143397 = r143395 / r143396;
        return r143397;
}

Error

Bits error versus x

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Target

Original19.9
Target0.7
Herbie0.5
\[\frac{1}{\left(x + 1\right) \cdot \sqrt{x} + x \cdot \sqrt{x + 1}}\]

Derivation

  1. Initial program 19.9

    \[\frac{1}{\sqrt{x}} - \frac{1}{\sqrt{x + 1}}\]
  2. Using strategy rm

  3. Applied frac-sub19.9

    \[\leadsto \color{blue}{\frac{1 \cdot \sqrt{x + 1} - \sqrt{x} \cdot 1}{\sqrt{x} \cdot \sqrt{x + 1}}}\]

  4. Simplified19.9

    \[\leadsto \frac{\color{blue}{1 \cdot \left(\sqrt{x + 1} - \sqrt{x}\right)}}{\sqrt{x} \cdot \sqrt{x + 1}}\]
  5. Using strategy rm

  6. Applied flip--19.6

    \[\leadsto \frac{1 \cdot \color{blue}{\frac{\sqrt{x + 1} \cdot \sqrt{x + 1} - \sqrt{x} \cdot \sqrt{x}}{\sqrt{x + 1} + \sqrt{x}}}}{\sqrt{x} \cdot \sqrt{x + 1}}\]

  7. Simplified19.2

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

  8. Taylor expanded around 0 0.4

    \[\leadsto \frac{1 \cdot \frac{\color{blue}{1}}{\sqrt{x + 1} + \sqrt{x}}}{\sqrt{x} \cdot \sqrt{x + 1}}\]
  9. Using strategy rm

  10. Applied add-cbrt-cube0.9

    \[\leadsto \frac{1 \cdot \frac{1}{\color{blue}{\sqrt[3]{\left(\left(\sqrt{x + 1} + \sqrt{x}\right) \cdot \left(\sqrt{x + 1} + \sqrt{x}\right)\right) \cdot \left(\sqrt{x + 1} + \sqrt{x}\right)}}}}{\sqrt{x} \cdot \sqrt{x + 1}}\]

  11. Applied add-cbrt-cube0.9

    \[\leadsto \frac{1 \cdot \frac{\color{blue}{\sqrt[3]{\left(1 \cdot 1\right) \cdot 1}}}{\sqrt[3]{\left(\left(\sqrt{x + 1} + \sqrt{x}\right) \cdot \left(\sqrt{x + 1} + \sqrt{x}\right)\right) \cdot \left(\sqrt{x + 1} + \sqrt{x}\right)}}}{\sqrt{x} \cdot \sqrt{x + 1}}\]

  12. Applied cbrt-undiv0.9

    \[\leadsto \frac{1 \cdot \color{blue}{\sqrt[3]{\frac{\left(1 \cdot 1\right) \cdot 1}{\left(\left(\sqrt{x + 1} + \sqrt{x}\right) \cdot \left(\sqrt{x + 1} + \sqrt{x}\right)\right) \cdot \left(\sqrt{x + 1} + \sqrt{x}\right)}}}}{\sqrt{x} \cdot \sqrt{x + 1}}\]

  13. Simplified0.5

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

  14. Final simplification0.5

    \[\leadsto \frac{1 \cdot \sqrt[3]{{\left(\frac{1}{\sqrt{x + 1} + \sqrt{x}}\right)}^{3}}}{\sqrt{x} \cdot \sqrt{x + 1}}\]

Reproduce

herbie shell --seed 2020056 
(FPCore (x)
  :name "2isqrt (example 3.6)"
  :precision binary64

  :herbie-target
  (/ 1 (+ (* (+ x 1) (sqrt x)) (* x (sqrt (+ x 1)))))

  (- (/ 1 (sqrt x)) (/ 1 (sqrt (+ x 1)))))