Statistics.Math.RootFinding:ridders from math-functions-0.1.5.2

Average Error: 24.2 → 6.0

Time: 7.4s

Precision: binary64

Math

\[\frac{\left(x \cdot y\right) \cdot z}{\sqrt{z \cdot z - t \cdot a}}\]

↓

\[\begin{array}{l} \mathbf{if}\;z \le -1.3266678793411263 \cdot 10^{154}:\\ \;\;\;\;x \cdot \left(y \cdot \frac{z}{\frac{1}{2} \cdot \left(t \cdot \frac{a}{z}\right) - z}\right)\\ \mathbf{elif}\;z \le 5.331137027891388 \cdot 10^{54}:\\ \;\;\;\;y \cdot \left(x \cdot \frac{z}{\sqrt{z \cdot z - t \cdot a}}\right)\\ \mathbf{else}:\\ \;\;\;\;x \cdot y\\ \end{array}\]

C

double code(double x, double y, double z, double t, double a) {
	return ((double) (((double) (((double) (x * y)) * z)) / ((double) sqrt(((double) (((double) (z * z)) - ((double) (t * a))))))));
}

↓

double code(double x, double y, double z, double t, double a) {
	double VAR;
	if ((z <= -1.3266678793411263e+154)) {
		VAR = ((double) (x * ((double) (y * ((double) (z / ((double) (((double) (0.5 * ((double) (t * ((double) (a / z)))))) - z))))))));
	} else {
		double VAR_1;
		if ((z <= 5.331137027891388e+54)) {
			VAR_1 = ((double) (y * ((double) (x * ((double) (z / ((double) sqrt(((double) (((double) (z * z)) - ((double) (t * a))))))))))));
		} else {
			VAR_1 = ((double) (x * y));
		}
		VAR = VAR_1;
	}
	return VAR;
}

Error

Bits error versus x

Bits error versus y

Bits error versus z

Bits error versus t

Bits error versus a

Target

Original	24.2
Target	7.2
Herbie	6.0

\[\begin{array}{l} \mathbf{if}\;z \lt -3.1921305903852764 \cdot 10^{46}:\\ \;\;\;\;-y \cdot x\\ \mathbf{elif}\;z \lt 5.9762681209208942 \cdot 10^{90}:\\ \;\;\;\;\frac{x \cdot z}{\frac{\sqrt{z \cdot z - a \cdot t}}{y}}\\ \mathbf{else}:\\ \;\;\;\;y \cdot x\\ \end{array}\]

Derivation

1. Split input into 3 regimes

2. if z < -1.3266678793411263e154

   1. Initial program 53.2

      \[\frac{\left(x \cdot y\right) \cdot z}{\sqrt{z \cdot z - t \cdot a}}\]

   2. Simplified 53.4

      \[\leadsto \color{blue}{x \cdot \left(y \cdot \frac{z}{\sqrt{z \cdot z - t \cdot a}}\right)}\]

   3. Taylor expanded around -inf 4.7

      \[\leadsto x \cdot \left(y \cdot \frac{z}{\color{blue}{\frac{1}{2} \cdot \frac{a \cdot t}{z} - z}}\right)\]

   4. Simplified 0.9

      \[\leadsto x \cdot \left(y \cdot \frac{z}{\color{blue}{\frac{1}{2} \cdot \left(t \cdot \frac{a}{z}\right) - z}}\right)\]

   if -1.3266678793411263e154 < z < 5.331137027891388e54

   1. Initial program 10.4

      \[\frac{\left(x \cdot y\right) \cdot z}{\sqrt{z \cdot z - t \cdot a}}\]

   2. Simplified 8.9

      \[\leadsto \color{blue}{x \cdot \left(y \cdot \frac{z}{\sqrt{z \cdot z - t \cdot a}}\right)}\]
   3. Using strategy rm

   4. Applied pow1 8.9

      \[\leadsto x \cdot \left(y \cdot \color{blue}{{\left(\frac{z}{\sqrt{z \cdot z - t \cdot a}}\right)}^{1}}\right)\]

   5. Applied pow1 8.9

      \[\leadsto x \cdot \left(\color{blue}{{y}^{1}} \cdot {\left(\frac{z}{\sqrt{z \cdot z - t \cdot a}}\right)}^{1}\right)\]

   6. Applied pow-prod-down 8.9

      \[\leadsto x \cdot \color{blue}{{\left(y \cdot \frac{z}{\sqrt{z \cdot z - t \cdot a}}\right)}^{1}}\]

   7. Applied pow1 8.9

      \[\leadsto \color{blue}{{x}^{1}} \cdot {\left(y \cdot \frac{z}{\sqrt{z \cdot z - t \cdot a}}\right)}^{1}\]

   8. Applied pow-prod-down 8.9

      \[\leadsto \color{blue}{{\left(x \cdot \left(y \cdot \frac{z}{\sqrt{z \cdot z - t \cdot a}}\right)\right)}^{1}}\]

   9. Simplified 8.5

      \[\leadsto {\color{blue}{\left(y \cdot \left(\frac{z}{\sqrt{z \cdot z - t \cdot a}} \cdot x\right)\right)}}^{1}\]

   if 5.331137027891388e54 < z

   1. Initial program 38.5

      \[\frac{\left(x \cdot y\right) \cdot z}{\sqrt{z \cdot z - t \cdot a}}\]

   2. Simplified 36.2

      \[\leadsto \color{blue}{x \cdot \left(y \cdot \frac{z}{\sqrt{z \cdot z - t \cdot a}}\right)}\]

   3. Taylor expanded around inf 3.3

      \[\leadsto x \cdot \color{blue}{y}\]
3. Recombined 3 regimes into one program.

4. Final simplification 6.0

   \[\leadsto \begin{array}{l} \mathbf{if}\;z \le -1.3266678793411263 \cdot 10^{154}:\\ \;\;\;\;x \cdot \left(y \cdot \frac{z}{\frac{1}{2} \cdot \left(t \cdot \frac{a}{z}\right) - z}\right)\\ \mathbf{elif}\;z \le 5.331137027891388 \cdot 10^{54}:\\ \;\;\;\;y \cdot \left(x \cdot \frac{z}{\sqrt{z \cdot z - t \cdot a}}\right)\\ \mathbf{else}:\\ \;\;\;\;x \cdot y\\ \end{array}\]

Reproduce

herbie shell --seed 2020184 
(FPCore (x y z t a)
  :name "Statistics.Math.RootFinding:ridders from math-functions-0.1.5.2"
  :precision binary64

  :herbie-target
  (if (< z -3.1921305903852764e+46) (neg (* y x)) (if (< z 5.976268120920894e+90) (/ (* x z) (/ (sqrt (- (* z z) (* a t))) y)) (* y x)))

  (/ (* (* x y) z) (sqrt (- (* z z) (* t a)))))