Given's Rotation SVD example

Percentage Accurate: 80.0% → 99.7%
Time: 9.8s
Alternatives: 4
Speedup: 0.7×

Specification

?
\[10^{-150} < \left|x\right| \land \left|x\right| < 10^{+150}\]
\[\begin{array}{l} \\ \sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \end{array} \]
(FPCore (p x)
 :precision binary64
 (sqrt (* 0.5 (+ 1.0 (/ x (sqrt (+ (* (* 4.0 p) p) (* x x))))))))
double code(double p, double x) {
	return sqrt((0.5 * (1.0 + (x / sqrt((((4.0 * p) * p) + (x * x)))))));
}
real(8) function code(p, x)
    real(8), intent (in) :: p
    real(8), intent (in) :: x
    code = sqrt((0.5d0 * (1.0d0 + (x / sqrt((((4.0d0 * p) * p) + (x * x)))))))
end function
public static double code(double p, double x) {
	return Math.sqrt((0.5 * (1.0 + (x / Math.sqrt((((4.0 * p) * p) + (x * x)))))));
}
def code(p, x):
	return math.sqrt((0.5 * (1.0 + (x / math.sqrt((((4.0 * p) * p) + (x * x)))))))
function code(p, x)
	return sqrt(Float64(0.5 * Float64(1.0 + Float64(x / sqrt(Float64(Float64(Float64(4.0 * p) * p) + Float64(x * x)))))))
end
function tmp = code(p, x)
	tmp = sqrt((0.5 * (1.0 + (x / sqrt((((4.0 * p) * p) + (x * x)))))));
end
code[p_, x_] := N[Sqrt[N[(0.5 * N[(1.0 + N[(x / N[Sqrt[N[(N[(N[(4.0 * p), $MachinePrecision] * p), $MachinePrecision] + N[(x * x), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)}
\end{array}

Sampling outcomes in binary64 precision:

Local Percentage Accuracy vs ?

The average percentage accuracy by input value. Horizontal axis shows value of an input variable; the variable is choosen in the title. Vertical axis is accuracy; higher is better. Red represent the original program, while blue represents Herbie's suggestion. These can be toggled with buttons below the plot. The line is an average while dots represent individual samples.

Accuracy vs Speed?

Herbie found 4 alternatives:

AlternativeAccuracySpeedup
The accuracy (vertical axis) and speed (horizontal axis) of each alternatives. Up and to the right is better. The red square shows the initial program, and each blue circle shows an alternative.The line shows the best available speed-accuracy tradeoffs.

Initial Program: 80.0% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \end{array} \]
(FPCore (p x)
 :precision binary64
 (sqrt (* 0.5 (+ 1.0 (/ x (sqrt (+ (* (* 4.0 p) p) (* x x))))))))
double code(double p, double x) {
	return sqrt((0.5 * (1.0 + (x / sqrt((((4.0 * p) * p) + (x * x)))))));
}
real(8) function code(p, x)
    real(8), intent (in) :: p
    real(8), intent (in) :: x
    code = sqrt((0.5d0 * (1.0d0 + (x / sqrt((((4.0d0 * p) * p) + (x * x)))))))
end function
public static double code(double p, double x) {
	return Math.sqrt((0.5 * (1.0 + (x / Math.sqrt((((4.0 * p) * p) + (x * x)))))));
}
def code(p, x):
	return math.sqrt((0.5 * (1.0 + (x / math.sqrt((((4.0 * p) * p) + (x * x)))))))
function code(p, x)
	return sqrt(Float64(0.5 * Float64(1.0 + Float64(x / sqrt(Float64(Float64(Float64(4.0 * p) * p) + Float64(x * x)))))))
end
function tmp = code(p, x)
	tmp = sqrt((0.5 * (1.0 + (x / sqrt((((4.0 * p) * p) + (x * x)))))));
end
code[p_, x_] := N[Sqrt[N[(0.5 * N[(1.0 + N[(x / N[Sqrt[N[(N[(N[(4.0 * p), $MachinePrecision] * p), $MachinePrecision] + N[(x * x), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)}
\end{array}

Alternative 1: 99.7% accurate, 0.7× speedup?

\[\begin{array}{l} p_m = \left|p\right| \\ \begin{array}{l} \mathbf{if}\;\frac{x}{\sqrt{p_m \cdot \left(4 \cdot p_m\right) + x \cdot x}} \leq -0.5:\\ \;\;\;\;\frac{-p_m}{x}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{\left(1 + \frac{x}{\mathsf{hypot}\left(x, p_m \cdot 2\right)}\right) \cdot 0.5}\\ \end{array} \end{array} \]
p_m = (fabs.f64 p)
(FPCore (p_m x)
 :precision binary64
 (if (<= (/ x (sqrt (+ (* p_m (* 4.0 p_m)) (* x x)))) -0.5)
   (/ (- p_m) x)
   (sqrt (* (+ 1.0 (/ x (hypot x (* p_m 2.0)))) 0.5))))
p_m = fabs(p);
double code(double p_m, double x) {
	double tmp;
	if ((x / sqrt(((p_m * (4.0 * p_m)) + (x * x)))) <= -0.5) {
		tmp = -p_m / x;
	} else {
		tmp = sqrt(((1.0 + (x / hypot(x, (p_m * 2.0)))) * 0.5));
	}
	return tmp;
}
p_m = Math.abs(p);
public static double code(double p_m, double x) {
	double tmp;
	if ((x / Math.sqrt(((p_m * (4.0 * p_m)) + (x * x)))) <= -0.5) {
		tmp = -p_m / x;
	} else {
		tmp = Math.sqrt(((1.0 + (x / Math.hypot(x, (p_m * 2.0)))) * 0.5));
	}
	return tmp;
}
p_m = math.fabs(p)
def code(p_m, x):
	tmp = 0
	if (x / math.sqrt(((p_m * (4.0 * p_m)) + (x * x)))) <= -0.5:
		tmp = -p_m / x
	else:
		tmp = math.sqrt(((1.0 + (x / math.hypot(x, (p_m * 2.0)))) * 0.5))
	return tmp
p_m = abs(p)
function code(p_m, x)
	tmp = 0.0
	if (Float64(x / sqrt(Float64(Float64(p_m * Float64(4.0 * p_m)) + Float64(x * x)))) <= -0.5)
		tmp = Float64(Float64(-p_m) / x);
	else
		tmp = sqrt(Float64(Float64(1.0 + Float64(x / hypot(x, Float64(p_m * 2.0)))) * 0.5));
	end
	return tmp
end
p_m = abs(p);
function tmp_2 = code(p_m, x)
	tmp = 0.0;
	if ((x / sqrt(((p_m * (4.0 * p_m)) + (x * x)))) <= -0.5)
		tmp = -p_m / x;
	else
		tmp = sqrt(((1.0 + (x / hypot(x, (p_m * 2.0)))) * 0.5));
	end
	tmp_2 = tmp;
end
p_m = N[Abs[p], $MachinePrecision]
code[p$95$m_, x_] := If[LessEqual[N[(x / N[Sqrt[N[(N[(p$95$m * N[(4.0 * p$95$m), $MachinePrecision]), $MachinePrecision] + N[(x * x), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision], -0.5], N[((-p$95$m) / x), $MachinePrecision], N[Sqrt[N[(N[(1.0 + N[(x / N[Sqrt[x ^ 2 + N[(p$95$m * 2.0), $MachinePrecision] ^ 2], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] * 0.5), $MachinePrecision]], $MachinePrecision]]
\begin{array}{l}
p_m = \left|p\right|

\\
\begin{array}{l}
\mathbf{if}\;\frac{x}{\sqrt{p_m \cdot \left(4 \cdot p_m\right) + x \cdot x}} \leq -0.5:\\
\;\;\;\;\frac{-p_m}{x}\\

\mathbf{else}:\\
\;\;\;\;\sqrt{\left(1 + \frac{x}{\mathsf{hypot}\left(x, p_m \cdot 2\right)}\right) \cdot 0.5}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (/.f64 x (sqrt.f64 (+.f64 (*.f64 (*.f64 4 p) p) (*.f64 x x)))) < -0.5

    1. Initial program 15.7%

      \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
    2. Simplified15.7%

      \[\leadsto \color{blue}{\sqrt{0.5 + 0.5 \cdot \frac{x}{\sqrt{\mathsf{fma}\left(x, x, 4 \cdot \left(p \cdot p\right)\right)}}}} \]
    3. Taylor expanded in x around -inf 57.5%

      \[\leadsto \color{blue}{-1 \cdot \frac{p}{x}} \]
    4. Step-by-step derivation
      1. mul-1-neg57.5%

        \[\leadsto \color{blue}{-\frac{p}{x}} \]
    5. Simplified57.5%

      \[\leadsto \color{blue}{-\frac{p}{x}} \]

    if -0.5 < (/.f64 x (sqrt.f64 (+.f64 (*.f64 (*.f64 4 p) p) (*.f64 x x))))

    1. Initial program 99.9%

      \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
    2. Simplified99.9%

      \[\leadsto \color{blue}{\sqrt{0.5 + 0.5 \cdot \frac{x}{\sqrt{\mathsf{fma}\left(x, x, 4 \cdot \left(p \cdot p\right)\right)}}}} \]
    3. Step-by-step derivation
      1. *-commutative99.9%

        \[\leadsto \sqrt{0.5 + \color{blue}{\frac{x}{\sqrt{\mathsf{fma}\left(x, x, 4 \cdot \left(p \cdot p\right)\right)}} \cdot 0.5}} \]
      2. associate-*r*99.9%

        \[\leadsto \sqrt{0.5 + \frac{x}{\sqrt{\mathsf{fma}\left(x, x, \color{blue}{\left(4 \cdot p\right) \cdot p}\right)}} \cdot 0.5} \]
      3. fma-udef99.9%

        \[\leadsto \sqrt{0.5 + \frac{x}{\sqrt{\color{blue}{x \cdot x + \left(4 \cdot p\right) \cdot p}}} \cdot 0.5} \]
      4. +-commutative99.9%

        \[\leadsto \sqrt{0.5 + \frac{x}{\sqrt{\color{blue}{\left(4 \cdot p\right) \cdot p + x \cdot x}}} \cdot 0.5} \]
      5. distribute-rgt1-in99.9%

        \[\leadsto \sqrt{\color{blue}{\left(\frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}} + 1\right) \cdot 0.5}} \]
    4. Applied egg-rr100.0%

      \[\leadsto \sqrt{\color{blue}{\left(1 + \frac{x}{\mathsf{hypot}\left(x, p \cdot 2\right)}\right) \cdot 0.5}} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification88.7%

    \[\leadsto \begin{array}{l} \mathbf{if}\;\frac{x}{\sqrt{p \cdot \left(4 \cdot p\right) + x \cdot x}} \leq -0.5:\\ \;\;\;\;\frac{-p}{x}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{\left(1 + \frac{x}{\mathsf{hypot}\left(x, p \cdot 2\right)}\right) \cdot 0.5}\\ \end{array} \]

Alternative 2: 65.4% accurate, 2.0× speedup?

\[\begin{array}{l} p_m = \left|p\right| \\ \begin{array}{l} \mathbf{if}\;x \leq -3.4 \cdot 10^{-24}:\\ \;\;\;\;\frac{-p_m}{x}\\ \mathbf{elif}\;x \leq 1.1 \cdot 10^{-49}:\\ \;\;\;\;\sqrt{0.5}\\ \mathbf{else}:\\ \;\;\;\;1\\ \end{array} \end{array} \]
p_m = (fabs.f64 p)
(FPCore (p_m x)
 :precision binary64
 (if (<= x -3.4e-24) (/ (- p_m) x) (if (<= x 1.1e-49) (sqrt 0.5) 1.0)))
p_m = fabs(p);
double code(double p_m, double x) {
	double tmp;
	if (x <= -3.4e-24) {
		tmp = -p_m / x;
	} else if (x <= 1.1e-49) {
		tmp = sqrt(0.5);
	} else {
		tmp = 1.0;
	}
	return tmp;
}
p_m = abs(p)
real(8) function code(p_m, x)
    real(8), intent (in) :: p_m
    real(8), intent (in) :: x
    real(8) :: tmp
    if (x <= (-3.4d-24)) then
        tmp = -p_m / x
    else if (x <= 1.1d-49) then
        tmp = sqrt(0.5d0)
    else
        tmp = 1.0d0
    end if
    code = tmp
end function
p_m = Math.abs(p);
public static double code(double p_m, double x) {
	double tmp;
	if (x <= -3.4e-24) {
		tmp = -p_m / x;
	} else if (x <= 1.1e-49) {
		tmp = Math.sqrt(0.5);
	} else {
		tmp = 1.0;
	}
	return tmp;
}
p_m = math.fabs(p)
def code(p_m, x):
	tmp = 0
	if x <= -3.4e-24:
		tmp = -p_m / x
	elif x <= 1.1e-49:
		tmp = math.sqrt(0.5)
	else:
		tmp = 1.0
	return tmp
p_m = abs(p)
function code(p_m, x)
	tmp = 0.0
	if (x <= -3.4e-24)
		tmp = Float64(Float64(-p_m) / x);
	elseif (x <= 1.1e-49)
		tmp = sqrt(0.5);
	else
		tmp = 1.0;
	end
	return tmp
end
p_m = abs(p);
function tmp_2 = code(p_m, x)
	tmp = 0.0;
	if (x <= -3.4e-24)
		tmp = -p_m / x;
	elseif (x <= 1.1e-49)
		tmp = sqrt(0.5);
	else
		tmp = 1.0;
	end
	tmp_2 = tmp;
end
p_m = N[Abs[p], $MachinePrecision]
code[p$95$m_, x_] := If[LessEqual[x, -3.4e-24], N[((-p$95$m) / x), $MachinePrecision], If[LessEqual[x, 1.1e-49], N[Sqrt[0.5], $MachinePrecision], 1.0]]
\begin{array}{l}
p_m = \left|p\right|

\\
\begin{array}{l}
\mathbf{if}\;x \leq -3.4 \cdot 10^{-24}:\\
\;\;\;\;\frac{-p_m}{x}\\

\mathbf{elif}\;x \leq 1.1 \cdot 10^{-49}:\\
\;\;\;\;\sqrt{0.5}\\

\mathbf{else}:\\
\;\;\;\;1\\


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if x < -3.39999999999999992e-24

    1. Initial program 46.8%

      \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
    2. Simplified46.8%

      \[\leadsto \color{blue}{\sqrt{0.5 + 0.5 \cdot \frac{x}{\sqrt{\mathsf{fma}\left(x, x, 4 \cdot \left(p \cdot p\right)\right)}}}} \]
    3. Taylor expanded in x around -inf 40.5%

      \[\leadsto \color{blue}{-1 \cdot \frac{p}{x}} \]
    4. Step-by-step derivation
      1. mul-1-neg40.5%

        \[\leadsto \color{blue}{-\frac{p}{x}} \]
    5. Simplified40.5%

      \[\leadsto \color{blue}{-\frac{p}{x}} \]

    if -3.39999999999999992e-24 < x < 1.09999999999999995e-49

    1. Initial program 81.2%

      \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
    2. Taylor expanded in x around 0 72.4%

      \[\leadsto \color{blue}{\sqrt{0.5}} \]

    if 1.09999999999999995e-49 < x

    1. Initial program 99.8%

      \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
    2. Simplified99.8%

      \[\leadsto \color{blue}{\sqrt{0.5 + 0.5 \cdot \frac{x}{\sqrt{\mathsf{fma}\left(x, x, 4 \cdot \left(p \cdot p\right)\right)}}}} \]
    3. Taylor expanded in x around inf 70.2%

      \[\leadsto \color{blue}{1 + -0.5 \cdot \frac{{p}^{2}}{{x}^{2}}} \]
    4. Step-by-step derivation
      1. associate-*r/70.2%

        \[\leadsto 1 + \color{blue}{\frac{-0.5 \cdot {p}^{2}}{{x}^{2}}} \]
      2. *-commutative70.2%

        \[\leadsto 1 + \frac{\color{blue}{{p}^{2} \cdot -0.5}}{{x}^{2}} \]
    5. Simplified70.2%

      \[\leadsto \color{blue}{1 + \frac{{p}^{2} \cdot -0.5}{{x}^{2}}} \]
    6. Step-by-step derivation
      1. unpow270.2%

        \[\leadsto 1 + \frac{{p}^{2} \cdot -0.5}{\color{blue}{x \cdot x}} \]
      2. times-frac70.2%

        \[\leadsto 1 + \color{blue}{\frac{{p}^{2}}{x} \cdot \frac{-0.5}{x}} \]
    7. Applied egg-rr70.2%

      \[\leadsto 1 + \color{blue}{\frac{{p}^{2}}{x} \cdot \frac{-0.5}{x}} \]
    8. Taylor expanded in p around 0 74.8%

      \[\leadsto \color{blue}{1} \]
  3. Recombined 3 regimes into one program.
  4. Final simplification64.5%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -3.4 \cdot 10^{-24}:\\ \;\;\;\;\frac{-p}{x}\\ \mathbf{elif}\;x \leq 1.1 \cdot 10^{-49}:\\ \;\;\;\;\sqrt{0.5}\\ \mathbf{else}:\\ \;\;\;\;1\\ \end{array} \]

Alternative 3: 55.5% accurate, 35.5× speedup?

\[\begin{array}{l} p_m = \left|p\right| \\ \begin{array}{l} \mathbf{if}\;x \leq -1.4 \cdot 10^{-145}:\\ \;\;\;\;\frac{-p_m}{x}\\ \mathbf{else}:\\ \;\;\;\;1\\ \end{array} \end{array} \]
p_m = (fabs.f64 p)
(FPCore (p_m x) :precision binary64 (if (<= x -1.4e-145) (/ (- p_m) x) 1.0))
p_m = fabs(p);
double code(double p_m, double x) {
	double tmp;
	if (x <= -1.4e-145) {
		tmp = -p_m / x;
	} else {
		tmp = 1.0;
	}
	return tmp;
}
p_m = abs(p)
real(8) function code(p_m, x)
    real(8), intent (in) :: p_m
    real(8), intent (in) :: x
    real(8) :: tmp
    if (x <= (-1.4d-145)) then
        tmp = -p_m / x
    else
        tmp = 1.0d0
    end if
    code = tmp
end function
p_m = Math.abs(p);
public static double code(double p_m, double x) {
	double tmp;
	if (x <= -1.4e-145) {
		tmp = -p_m / x;
	} else {
		tmp = 1.0;
	}
	return tmp;
}
p_m = math.fabs(p)
def code(p_m, x):
	tmp = 0
	if x <= -1.4e-145:
		tmp = -p_m / x
	else:
		tmp = 1.0
	return tmp
p_m = abs(p)
function code(p_m, x)
	tmp = 0.0
	if (x <= -1.4e-145)
		tmp = Float64(Float64(-p_m) / x);
	else
		tmp = 1.0;
	end
	return tmp
end
p_m = abs(p);
function tmp_2 = code(p_m, x)
	tmp = 0.0;
	if (x <= -1.4e-145)
		tmp = -p_m / x;
	else
		tmp = 1.0;
	end
	tmp_2 = tmp;
end
p_m = N[Abs[p], $MachinePrecision]
code[p$95$m_, x_] := If[LessEqual[x, -1.4e-145], N[((-p$95$m) / x), $MachinePrecision], 1.0]
\begin{array}{l}
p_m = \left|p\right|

\\
\begin{array}{l}
\mathbf{if}\;x \leq -1.4 \cdot 10^{-145}:\\
\;\;\;\;\frac{-p_m}{x}\\

\mathbf{else}:\\
\;\;\;\;1\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < -1.4000000000000001e-145

    1. Initial program 56.6%

      \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
    2. Simplified56.6%

      \[\leadsto \color{blue}{\sqrt{0.5 + 0.5 \cdot \frac{x}{\sqrt{\mathsf{fma}\left(x, x, 4 \cdot \left(p \cdot p\right)\right)}}}} \]
    3. Taylor expanded in x around -inf 31.2%

      \[\leadsto \color{blue}{-1 \cdot \frac{p}{x}} \]
    4. Step-by-step derivation
      1. mul-1-neg31.2%

        \[\leadsto \color{blue}{-\frac{p}{x}} \]
    5. Simplified31.2%

      \[\leadsto \color{blue}{-\frac{p}{x}} \]

    if -1.4000000000000001e-145 < x

    1. Initial program 99.8%

      \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
    2. Simplified99.8%

      \[\leadsto \color{blue}{\sqrt{0.5 + 0.5 \cdot \frac{x}{\sqrt{\mathsf{fma}\left(x, x, 4 \cdot \left(p \cdot p\right)\right)}}}} \]
    3. Taylor expanded in x around inf 51.9%

      \[\leadsto \color{blue}{1 + -0.5 \cdot \frac{{p}^{2}}{{x}^{2}}} \]
    4. Step-by-step derivation
      1. associate-*r/51.9%

        \[\leadsto 1 + \color{blue}{\frac{-0.5 \cdot {p}^{2}}{{x}^{2}}} \]
      2. *-commutative51.9%

        \[\leadsto 1 + \frac{\color{blue}{{p}^{2} \cdot -0.5}}{{x}^{2}} \]
    5. Simplified51.9%

      \[\leadsto \color{blue}{1 + \frac{{p}^{2} \cdot -0.5}{{x}^{2}}} \]
    6. Step-by-step derivation
      1. unpow251.9%

        \[\leadsto 1 + \frac{{p}^{2} \cdot -0.5}{\color{blue}{x \cdot x}} \]
      2. times-frac51.9%

        \[\leadsto 1 + \color{blue}{\frac{{p}^{2}}{x} \cdot \frac{-0.5}{x}} \]
    7. Applied egg-rr51.9%

      \[\leadsto 1 + \color{blue}{\frac{{p}^{2}}{x} \cdot \frac{-0.5}{x}} \]
    8. Taylor expanded in p around 0 60.2%

      \[\leadsto \color{blue}{1} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification45.3%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -1.4 \cdot 10^{-145}:\\ \;\;\;\;\frac{-p}{x}\\ \mathbf{else}:\\ \;\;\;\;1\\ \end{array} \]

Alternative 4: 36.6% accurate, 215.0× speedup?

\[\begin{array}{l} p_m = \left|p\right| \\ 1 \end{array} \]
p_m = (fabs.f64 p)
(FPCore (p_m x) :precision binary64 1.0)
p_m = fabs(p);
double code(double p_m, double x) {
	return 1.0;
}
p_m = abs(p)
real(8) function code(p_m, x)
    real(8), intent (in) :: p_m
    real(8), intent (in) :: x
    code = 1.0d0
end function
p_m = Math.abs(p);
public static double code(double p_m, double x) {
	return 1.0;
}
p_m = math.fabs(p)
def code(p_m, x):
	return 1.0
p_m = abs(p)
function code(p_m, x)
	return 1.0
end
p_m = abs(p);
function tmp = code(p_m, x)
	tmp = 1.0;
end
p_m = N[Abs[p], $MachinePrecision]
code[p$95$m_, x_] := 1.0
\begin{array}{l}
p_m = \left|p\right|

\\
1
\end{array}
Derivation
  1. Initial program 77.5%

    \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
  2. Simplified77.5%

    \[\leadsto \color{blue}{\sqrt{0.5 + 0.5 \cdot \frac{x}{\sqrt{\mathsf{fma}\left(x, x, 4 \cdot \left(p \cdot p\right)\right)}}}} \]
  3. Taylor expanded in x around inf 26.8%

    \[\leadsto \color{blue}{1 + -0.5 \cdot \frac{{p}^{2}}{{x}^{2}}} \]
  4. Step-by-step derivation
    1. associate-*r/26.8%

      \[\leadsto 1 + \color{blue}{\frac{-0.5 \cdot {p}^{2}}{{x}^{2}}} \]
    2. *-commutative26.8%

      \[\leadsto 1 + \frac{\color{blue}{{p}^{2} \cdot -0.5}}{{x}^{2}} \]
  5. Simplified26.8%

    \[\leadsto \color{blue}{1 + \frac{{p}^{2} \cdot -0.5}{{x}^{2}}} \]
  6. Step-by-step derivation
    1. unpow226.8%

      \[\leadsto 1 + \frac{{p}^{2} \cdot -0.5}{\color{blue}{x \cdot x}} \]
    2. times-frac26.8%

      \[\leadsto 1 + \color{blue}{\frac{{p}^{2}}{x} \cdot \frac{-0.5}{x}} \]
  7. Applied egg-rr26.8%

    \[\leadsto 1 + \color{blue}{\frac{{p}^{2}}{x} \cdot \frac{-0.5}{x}} \]
  8. Taylor expanded in p around 0 35.6%

    \[\leadsto \color{blue}{1} \]
  9. Final simplification35.6%

    \[\leadsto 1 \]

Developer target: 80.0% accurate, 0.7× speedup?

\[\begin{array}{l} \\ \sqrt{0.5 + \frac{\mathsf{copysign}\left(0.5, x\right)}{\mathsf{hypot}\left(1, \frac{2 \cdot p}{x}\right)}} \end{array} \]
(FPCore (p x)
 :precision binary64
 (sqrt (+ 0.5 (/ (copysign 0.5 x) (hypot 1.0 (/ (* 2.0 p) x))))))
double code(double p, double x) {
	return sqrt((0.5 + (copysign(0.5, x) / hypot(1.0, ((2.0 * p) / x)))));
}
public static double code(double p, double x) {
	return Math.sqrt((0.5 + (Math.copySign(0.5, x) / Math.hypot(1.0, ((2.0 * p) / x)))));
}
def code(p, x):
	return math.sqrt((0.5 + (math.copysign(0.5, x) / math.hypot(1.0, ((2.0 * p) / x)))))
function code(p, x)
	return sqrt(Float64(0.5 + Float64(copysign(0.5, x) / hypot(1.0, Float64(Float64(2.0 * p) / x)))))
end
function tmp = code(p, x)
	tmp = sqrt((0.5 + ((sign(x) * abs(0.5)) / hypot(1.0, ((2.0 * p) / x)))));
end
code[p_, x_] := N[Sqrt[N[(0.5 + N[(N[With[{TMP1 = Abs[0.5], TMP2 = Sign[x]}, TMP1 * If[TMP2 == 0, 1, TMP2]], $MachinePrecision] / N[Sqrt[1.0 ^ 2 + N[(N[(2.0 * p), $MachinePrecision] / x), $MachinePrecision] ^ 2], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\sqrt{0.5 + \frac{\mathsf{copysign}\left(0.5, x\right)}{\mathsf{hypot}\left(1, \frac{2 \cdot p}{x}\right)}}
\end{array}

Reproduce

?
herbie shell --seed 2023336 
(FPCore (p x)
  :name "Given's Rotation SVD example"
  :precision binary64
  :pre (and (< 1e-150 (fabs x)) (< (fabs x) 1e+150))

  :herbie-target
  (sqrt (+ 0.5 (/ (copysign 0.5 x) (hypot 1.0 (/ (* 2.0 p) x)))))

  (sqrt (* 0.5 (+ 1.0 (/ x (sqrt (+ (* (* 4.0 p) p) (* x x))))))))