Numeric.SpecFunctions:stirlingError from math-functions-0.1.5.2

Average Error: 0.1 → 0.2

Time: 8.0min

Precision: binary64

• Falling back on racket egraph because egg-herbie package not installed

Math

\[\left(\left(x - \left(y + 0.5\right) \cdot \log y\right) + y\right) - z\]

↓

\[\left(\left(x - \left(\left(y + 0.5\right) \cdot \left(2 \cdot \log \left(\sqrt[3]{y}\right) + \log \left(\sqrt[3]{\sqrt{y}}\right)\right) + \left(y + 0.5\right) \cdot \log \left(\sqrt[3]{\sqrt{y}}\right)\right)\right) + y\right) - z\]

C

double code(double x, double y, double z) {
	return ((double) (((double) (((double) (x - ((double) (((double) (y + 0.5)) * ((double) log(y)))))) + y)) - z));
}

↓

double code(double x, double y, double z) {
	return ((double) (((double) (((double) (x - ((double) (((double) (((double) (y + 0.5)) * ((double) (((double) (2.0 * ((double) log(((double) cbrt(y)))))) + ((double) log(((double) cbrt(((double) sqrt(y)))))))))) + ((double) (((double) (y + 0.5)) * ((double) log(((double) cbrt(((double) sqrt(y)))))))))))) + y)) - z));
}

Error

Bits error versus x

Bits error versus y

Bits error versus z

Target

Original	0.1
Target	0.1
Herbie	0.2

\[\left(\left(y + x\right) - z\right) - \left(y + 0.5\right) \cdot \log y\]

Derivation

1. Initial program 0.1

   \[\left(\left(x - \left(y + 0.5\right) \cdot \log y\right) + y\right) - z\]
2. Using strategy rm

3. Applied add-cube-cbrt 0.1

   \[\leadsto \left(\left(x - \left(y + 0.5\right) \cdot \log \color{blue}{\left(\left(\sqrt[3]{y} \cdot \sqrt[3]{y}\right) \cdot \sqrt[3]{y}\right)}\right) + y\right) - z\]

4. Applied log-prod 0.2

   \[\leadsto \left(\left(x - \left(y + 0.5\right) \cdot \color{blue}{\left(\log \left(\sqrt[3]{y} \cdot \sqrt[3]{y}\right) + \log \left(\sqrt[3]{y}\right)\right)}\right) + y\right) - z\]

5. Applied distribute-lft-in 0.2

   \[\leadsto \left(\left(x - \color{blue}{\left(\left(y + 0.5\right) \cdot \log \left(\sqrt[3]{y} \cdot \sqrt[3]{y}\right) + \left(y + 0.5\right) \cdot \log \left(\sqrt[3]{y}\right)\right)}\right) + y\right) - z\]

6. Simplified 0.2

   \[\leadsto \left(\left(x - \left(\color{blue}{\left(2 \cdot \log \left(\sqrt[3]{y}\right)\right) \cdot \left(y + 0.5\right)} + \left(y + 0.5\right) \cdot \log \left(\sqrt[3]{y}\right)\right)\right) + y\right) - z\]
7. Using strategy rm

8. Applied add-sqr-sqrt 0.2

   \[\leadsto \left(\left(x - \left(\left(2 \cdot \log \left(\sqrt[3]{y}\right)\right) \cdot \left(y + 0.5\right) + \left(y + 0.5\right) \cdot \log \left(\sqrt[3]{\color{blue}{\sqrt{y} \cdot \sqrt{y}}}\right)\right)\right) + y\right) - z\]

9. Applied cbrt-prod 0.2

   \[\leadsto \left(\left(x - \left(\left(2 \cdot \log \left(\sqrt[3]{y}\right)\right) \cdot \left(y + 0.5\right) + \left(y + 0.5\right) \cdot \log \color{blue}{\left(\sqrt[3]{\sqrt{y}} \cdot \sqrt[3]{\sqrt{y}}\right)}\right)\right) + y\right) - z\]

10. Applied log-prod 0.2

    \[\leadsto \left(\left(x - \left(\left(2 \cdot \log \left(\sqrt[3]{y}\right)\right) \cdot \left(y + 0.5\right) + \left(y + 0.5\right) \cdot \color{blue}{\left(\log \left(\sqrt[3]{\sqrt{y}}\right) + \log \left(\sqrt[3]{\sqrt{y}}\right)\right)}\right)\right) + y\right) - z\]

11. Applied distribute-lft-in 0.2

    \[\leadsto \left(\left(x - \left(\left(2 \cdot \log \left(\sqrt[3]{y}\right)\right) \cdot \left(y + 0.5\right) + \color{blue}{\left(\left(y + 0.5\right) \cdot \log \left(\sqrt[3]{\sqrt{y}}\right) + \left(y + 0.5\right) \cdot \log \left(\sqrt[3]{\sqrt{y}}\right)\right)}\right)\right) + y\right) - z\]

12. Applied associate-+r+ 0.2

    \[\leadsto \left(\left(x - \color{blue}{\left(\left(\left(2 \cdot \log \left(\sqrt[3]{y}\right)\right) \cdot \left(y + 0.5\right) + \left(y + 0.5\right) \cdot \log \left(\sqrt[3]{\sqrt{y}}\right)\right) + \left(y + 0.5\right) \cdot \log \left(\sqrt[3]{\sqrt{y}}\right)\right)}\right) + y\right) - z\]

13. Simplified 0.2

    \[\leadsto \left(\left(x - \left(\color{blue}{\left(y + 0.5\right) \cdot \left(2 \cdot \log \left(\sqrt[3]{y}\right) + \log \left(\sqrt[3]{\sqrt{y}}\right)\right)} + \left(y + 0.5\right) \cdot \log \left(\sqrt[3]{\sqrt{y}}\right)\right)\right) + y\right) - z\]

14. Final simplification 0.2

    \[\leadsto \left(\left(x - \left(\left(y + 0.5\right) \cdot \left(2 \cdot \log \left(\sqrt[3]{y}\right) + \log \left(\sqrt[3]{\sqrt{y}}\right)\right) + \left(y + 0.5\right) \cdot \log \left(\sqrt[3]{\sqrt{y}}\right)\right)\right) + y\right) - z\]

Reproduce

herbie shell --seed 2020181 
(FPCore (x y z)
  :name "Numeric.SpecFunctions:stirlingError from math-functions-0.1.5.2"
  :precision binary64

  :herbie-target
  (- (- (+ y x) z) (* (+ y 0.5) (log y)))

  (- (+ (- x (* (+ y 0.5) (log y))) y) z))