Average Error: 21.2 → 0.4
Time: 1.2s
Precision: binary64
\[\sqrt{x \cdot x + y}\]
↓
\[\begin{array}{l} \mathbf{if}\;x \leq -1.5013366581586753 \cdot 10^{+152}:\\ \;\;\;\;y \cdot \frac{-0.5}{x} - x\\ \mathbf{elif}\;x \leq 8.691984318156497 \cdot 10^{+77}:\\ \;\;\;\;\sqrt{y + x \cdot x}\\ \mathbf{else}:\\ \;\;\;\;x + 0.5 \cdot \frac{y}{x}\\ \end{array}\]
\sqrt{x \cdot x + y}
↓
\begin{array}{l}
\mathbf{if}\;x \leq -1.5013366581586753 \cdot 10^{+152}:\\
\;\;\;\;y \cdot \frac{-0.5}{x} - x\\

\mathbf{elif}\;x \leq 8.691984318156497 \cdot 10^{+77}:\\
\;\;\;\;\sqrt{y + x \cdot x}\\

\mathbf{else}:\\
\;\;\;\;x + 0.5 \cdot \frac{y}{x}\\

\end{array}
(FPCore (x y) :precision binary64 (sqrt (+ (* x x) y)))
↓
(FPCore (x y)
 :precision binary64
 (if (<= x -1.5013366581586753e+152)
   (- (* y (/ -0.5 x)) x)
   (if (<= x 8.691984318156497e+77)
     (sqrt (+ y (* x x)))
     (+ x (* 0.5 (/ y x))))))
double code(double x, double y) {
	return sqrt((x * x) + y);
}
↓
double code(double x, double y) {
	double tmp;
	if (x <= -1.5013366581586753e+152) {
		tmp = (y * (-0.5 / x)) - x;
	} else if (x <= 8.691984318156497e+77) {
		tmp = sqrt(y + (x * x));
	} else {
		tmp = x + (0.5 * (y / x));
	}
	return tmp;
}

Error

Bits error versus x

Bits error versus y

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Target

Original21.2
Target0.6
Herbie0.4
\[\begin{array}{l} \mathbf{if}\;x < -1.5097698010472593 \cdot 10^{+153}:\\ \;\;\;\;-\left(0.5 \cdot \frac{y}{x} + x\right)\\ \mathbf{elif}\;x < 5.582399551122541 \cdot 10^{+57}:\\ \;\;\;\;\sqrt{x \cdot x + y}\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \frac{y}{x} + x\\ \end{array}\]

Derivation

  1. Split input into 3 regimes

  2. if x < -1.50133665815867534e152

    1. Initial program 63.2

      \[\sqrt{x \cdot x + y}\]

    2. Taylor expanded around -inf 0

      \[\leadsto \color{blue}{-\left(x + 0.5 \cdot \frac{y}{x}\right)}\]

    3. Simplified0

      \[\leadsto \color{blue}{y \cdot \frac{-0.5}{x} - x}\]

    if -1.50133665815867534e152 < x < 8.69198431815649669e77

    1. Initial program 0.0

      \[\sqrt{x \cdot x + y}\]

    if 8.69198431815649669e77 < x

    1. Initial program 43.8

      \[\sqrt{x \cdot x + y}\]

    2. Taylor expanded around inf 1.6

      \[\leadsto \color{blue}{x + 0.5 \cdot \frac{y}{x}}\]
  3. Recombined 3 regimes into one program.

  4. Final simplification0.4

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -1.5013366581586753 \cdot 10^{+152}:\\ \;\;\;\;y \cdot \frac{-0.5}{x} - x\\ \mathbf{elif}\;x \leq 8.691984318156497 \cdot 10^{+77}:\\ \;\;\;\;\sqrt{y + x \cdot x}\\ \mathbf{else}:\\ \;\;\;\;x + 0.5 \cdot \frac{y}{x}\\ \end{array}\]

Reproduce

herbie shell --seed 2020224 
(FPCore (x y)
  :name "Linear.Quaternion:$clog from linear-1.19.1.3"
  :precision binary64

  :herbie-target
  (if (< x -1.5097698010472593e+153) (- (+ (* 0.5 (/ y x)) x)) (if (< x 5.582399551122541e+57) (sqrt (+ (* x x) y)) (+ (* 0.5 (/ y x)) x)))

  (sqrt (+ (* x x) y)))