Given's Rotation SVD example

Percentage Accurate: 79.6% → 99.7%
Time: 6.7s
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: 79.6% 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?

\[\begin{array}{l} p_m = \left|p\right| \\ \begin{array}{l} t_0 := \frac{x}{\sqrt{p\_m \cdot \left(4 \cdot p\_m\right) + x \cdot x}}\\ \mathbf{if}\;t\_0 \leq -1:\\ \;\;\;\;\frac{p\_m}{-x}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{0.5 \cdot \left(t\_0 + 1\right)}\\ \end{array} \end{array} \]
p_m = (fabs.f64 p)
(FPCore (p_m x)
 :precision binary64
 (let* ((t_0 (/ x (sqrt (+ (* p_m (* 4.0 p_m)) (* x x))))))
   (if (<= t_0 -1.0) (/ p_m (- x)) (sqrt (* 0.5 (+ t_0 1.0))))))
p_m = fabs(p);
double code(double p_m, double x) {
	double t_0 = x / sqrt(((p_m * (4.0 * p_m)) + (x * x)));
	double tmp;
	if (t_0 <= -1.0) {
		tmp = p_m / -x;
	} else {
		tmp = sqrt((0.5 * (t_0 + 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) :: t_0
    real(8) :: tmp
    t_0 = x / sqrt(((p_m * (4.0d0 * p_m)) + (x * x)))
    if (t_0 <= (-1.0d0)) then
        tmp = p_m / -x
    else
        tmp = sqrt((0.5d0 * (t_0 + 1.0d0)))
    end if
    code = tmp
end function
p_m = Math.abs(p);
public static double code(double p_m, double x) {
	double t_0 = x / Math.sqrt(((p_m * (4.0 * p_m)) + (x * x)));
	double tmp;
	if (t_0 <= -1.0) {
		tmp = p_m / -x;
	} else {
		tmp = Math.sqrt((0.5 * (t_0 + 1.0)));
	}
	return tmp;
}
p_m = math.fabs(p)
def code(p_m, x):
	t_0 = x / math.sqrt(((p_m * (4.0 * p_m)) + (x * x)))
	tmp = 0
	if t_0 <= -1.0:
		tmp = p_m / -x
	else:
		tmp = math.sqrt((0.5 * (t_0 + 1.0)))
	return tmp
p_m = abs(p)
function code(p_m, x)
	t_0 = Float64(x / sqrt(Float64(Float64(p_m * Float64(4.0 * p_m)) + Float64(x * x))))
	tmp = 0.0
	if (t_0 <= -1.0)
		tmp = Float64(p_m / Float64(-x));
	else
		tmp = sqrt(Float64(0.5 * Float64(t_0 + 1.0)));
	end
	return tmp
end
p_m = abs(p);
function tmp_2 = code(p_m, x)
	t_0 = x / sqrt(((p_m * (4.0 * p_m)) + (x * x)));
	tmp = 0.0;
	if (t_0 <= -1.0)
		tmp = p_m / -x;
	else
		tmp = sqrt((0.5 * (t_0 + 1.0)));
	end
	tmp_2 = tmp;
end
p_m = N[Abs[p], $MachinePrecision]
code[p$95$m_, x_] := Block[{t$95$0 = N[(x / N[Sqrt[N[(N[(p$95$m * N[(4.0 * p$95$m), $MachinePrecision]), $MachinePrecision] + N[(x * x), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, If[LessEqual[t$95$0, -1.0], N[(p$95$m / (-x)), $MachinePrecision], N[Sqrt[N[(0.5 * N[(t$95$0 + 1.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]]]
\begin{array}{l}
p_m = \left|p\right|

\\
\begin{array}{l}
t_0 := \frac{x}{\sqrt{p\_m \cdot \left(4 \cdot p\_m\right) + x \cdot x}}\\
\mathbf{if}\;t\_0 \leq -1:\\
\;\;\;\;\frac{p\_m}{-x}\\

\mathbf{else}:\\
\;\;\;\;\sqrt{0.5 \cdot \left(t\_0 + 1\right)}\\


\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)))) < -1

    1. Initial program 13.8%

      \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
    2. Add Preprocessing
    3. Taylor expanded in x around -inf 45.5%

      \[\leadsto \color{blue}{-1 \cdot \frac{p \cdot \left(\sqrt{0.5} \cdot \sqrt{2}\right)}{x}} \]
    4. Step-by-step derivation
      1. mul-1-neg45.5%

        \[\leadsto \color{blue}{-\frac{p \cdot \left(\sqrt{0.5} \cdot \sqrt{2}\right)}{x}} \]
    5. Simplified45.5%

      \[\leadsto \color{blue}{-\frac{p \cdot \left(\sqrt{0.5} \cdot \sqrt{2}\right)}{x}} \]
    6. Step-by-step derivation
      1. sqrt-unprod46.2%

        \[\leadsto -\frac{p \cdot \color{blue}{\sqrt{0.5 \cdot 2}}}{x} \]
      2. metadata-eval46.2%

        \[\leadsto -\frac{p \cdot \sqrt{\color{blue}{1}}}{x} \]
      3. metadata-eval46.2%

        \[\leadsto -\frac{p \cdot \color{blue}{1}}{x} \]
    7. Applied egg-rr46.2%

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

    if -1 < (/.f64 x (sqrt.f64 (+.f64 (*.f64 (*.f64 4 p) p) (*.f64 x x))))

    1. Initial program 100.0%

      \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
    2. Add Preprocessing
  3. Recombined 2 regimes into one program.
  4. Final simplification87.0%

    \[\leadsto \begin{array}{l} \mathbf{if}\;\frac{x}{\sqrt{p \cdot \left(4 \cdot p\right) + x \cdot x}} \leq -1:\\ \;\;\;\;\frac{p}{-x}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{0.5 \cdot \left(\frac{x}{\sqrt{p \cdot \left(4 \cdot p\right) + x \cdot x}} + 1\right)}\\ \end{array} \]
  5. Add Preprocessing

Alternative 2: 65.8% accurate, 1.8× speedup?

\[\begin{array}{l} p_m = \left|p\right| \\ \begin{array}{l} t_0 := \frac{p\_m}{-x}\\ \mathbf{if}\;x \leq -3.6 \cdot 10^{+31}:\\ \;\;\;\;t\_0\\ \mathbf{elif}\;x \leq -1850:\\ \;\;\;\;\sqrt{0.5}\\ \mathbf{elif}\;x \leq -2.45 \cdot 10^{-51}:\\ \;\;\;\;t\_0\\ \mathbf{elif}\;x \leq 20000000000000:\\ \;\;\;\;\sqrt{0.5}\\ \mathbf{else}:\\ \;\;\;\;1\\ \end{array} \end{array} \]
p_m = (fabs.f64 p)
(FPCore (p_m x)
 :precision binary64
 (let* ((t_0 (/ p_m (- x))))
   (if (<= x -3.6e+31)
     t_0
     (if (<= x -1850.0)
       (sqrt 0.5)
       (if (<= x -2.45e-51)
         t_0
         (if (<= x 20000000000000.0) (sqrt 0.5) 1.0))))))
p_m = fabs(p);
double code(double p_m, double x) {
	double t_0 = p_m / -x;
	double tmp;
	if (x <= -3.6e+31) {
		tmp = t_0;
	} else if (x <= -1850.0) {
		tmp = sqrt(0.5);
	} else if (x <= -2.45e-51) {
		tmp = t_0;
	} else if (x <= 20000000000000.0) {
		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) :: t_0
    real(8) :: tmp
    t_0 = p_m / -x
    if (x <= (-3.6d+31)) then
        tmp = t_0
    else if (x <= (-1850.0d0)) then
        tmp = sqrt(0.5d0)
    else if (x <= (-2.45d-51)) then
        tmp = t_0
    else if (x <= 20000000000000.0d0) 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 t_0 = p_m / -x;
	double tmp;
	if (x <= -3.6e+31) {
		tmp = t_0;
	} else if (x <= -1850.0) {
		tmp = Math.sqrt(0.5);
	} else if (x <= -2.45e-51) {
		tmp = t_0;
	} else if (x <= 20000000000000.0) {
		tmp = Math.sqrt(0.5);
	} else {
		tmp = 1.0;
	}
	return tmp;
}
p_m = math.fabs(p)
def code(p_m, x):
	t_0 = p_m / -x
	tmp = 0
	if x <= -3.6e+31:
		tmp = t_0
	elif x <= -1850.0:
		tmp = math.sqrt(0.5)
	elif x <= -2.45e-51:
		tmp = t_0
	elif x <= 20000000000000.0:
		tmp = math.sqrt(0.5)
	else:
		tmp = 1.0
	return tmp
p_m = abs(p)
function code(p_m, x)
	t_0 = Float64(p_m / Float64(-x))
	tmp = 0.0
	if (x <= -3.6e+31)
		tmp = t_0;
	elseif (x <= -1850.0)
		tmp = sqrt(0.5);
	elseif (x <= -2.45e-51)
		tmp = t_0;
	elseif (x <= 20000000000000.0)
		tmp = sqrt(0.5);
	else
		tmp = 1.0;
	end
	return tmp
end
p_m = abs(p);
function tmp_2 = code(p_m, x)
	t_0 = p_m / -x;
	tmp = 0.0;
	if (x <= -3.6e+31)
		tmp = t_0;
	elseif (x <= -1850.0)
		tmp = sqrt(0.5);
	elseif (x <= -2.45e-51)
		tmp = t_0;
	elseif (x <= 20000000000000.0)
		tmp = sqrt(0.5);
	else
		tmp = 1.0;
	end
	tmp_2 = tmp;
end
p_m = N[Abs[p], $MachinePrecision]
code[p$95$m_, x_] := Block[{t$95$0 = N[(p$95$m / (-x)), $MachinePrecision]}, If[LessEqual[x, -3.6e+31], t$95$0, If[LessEqual[x, -1850.0], N[Sqrt[0.5], $MachinePrecision], If[LessEqual[x, -2.45e-51], t$95$0, If[LessEqual[x, 20000000000000.0], N[Sqrt[0.5], $MachinePrecision], 1.0]]]]]
\begin{array}{l}
p_m = \left|p\right|

\\
\begin{array}{l}
t_0 := \frac{p\_m}{-x}\\
\mathbf{if}\;x \leq -3.6 \cdot 10^{+31}:\\
\;\;\;\;t\_0\\

\mathbf{elif}\;x \leq -1850:\\
\;\;\;\;\sqrt{0.5}\\

\mathbf{elif}\;x \leq -2.45 \cdot 10^{-51}:\\
\;\;\;\;t\_0\\

\mathbf{elif}\;x \leq 20000000000000:\\
\;\;\;\;\sqrt{0.5}\\

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


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if x < -3.59999999999999996e31 or -1850 < x < -2.44999999999999987e-51

    1. Initial program 37.8%

      \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
    2. Add Preprocessing
    3. Taylor expanded in x around -inf 34.5%

      \[\leadsto \color{blue}{-1 \cdot \frac{p \cdot \left(\sqrt{0.5} \cdot \sqrt{2}\right)}{x}} \]
    4. Step-by-step derivation
      1. mul-1-neg34.5%

        \[\leadsto \color{blue}{-\frac{p \cdot \left(\sqrt{0.5} \cdot \sqrt{2}\right)}{x}} \]
    5. Simplified34.5%

      \[\leadsto \color{blue}{-\frac{p \cdot \left(\sqrt{0.5} \cdot \sqrt{2}\right)}{x}} \]
    6. Step-by-step derivation
      1. sqrt-unprod35.0%

        \[\leadsto -\frac{p \cdot \color{blue}{\sqrt{0.5 \cdot 2}}}{x} \]
      2. metadata-eval35.0%

        \[\leadsto -\frac{p \cdot \sqrt{\color{blue}{1}}}{x} \]
      3. metadata-eval35.0%

        \[\leadsto -\frac{p \cdot \color{blue}{1}}{x} \]
    7. Applied egg-rr35.0%

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

    if -3.59999999999999996e31 < x < -1850 or -2.44999999999999987e-51 < x < 2e13

    1. Initial program 91.6%

      \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
    2. Add Preprocessing
    3. Taylor expanded in x around 0 78.0%

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

    if 2e13 < x

    1. Initial program 100.0%

      \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
    2. Add Preprocessing
    3. Taylor expanded in x around inf 70.3%

      \[\leadsto \sqrt{0.5 \cdot \color{blue}{2}} \]
  3. Recombined 3 regimes into one program.
  4. Final simplification64.6%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -3.6 \cdot 10^{+31}:\\ \;\;\;\;\frac{p}{-x}\\ \mathbf{elif}\;x \leq -1850:\\ \;\;\;\;\sqrt{0.5}\\ \mathbf{elif}\;x \leq -2.45 \cdot 10^{-51}:\\ \;\;\;\;\frac{p}{-x}\\ \mathbf{elif}\;x \leq 20000000000000:\\ \;\;\;\;\sqrt{0.5}\\ \mathbf{else}:\\ \;\;\;\;1\\ \end{array} \]
  5. Add Preprocessing

Alternative 3: 68.3% accurate, 2.0× speedup?

\[\begin{array}{l} p_m = \left|p\right| \\ \begin{array}{l} \mathbf{if}\;p\_m \leq 2.2 \cdot 10^{-75}:\\ \;\;\;\;\frac{p\_m}{-x}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{0.5}\\ \end{array} \end{array} \]
p_m = (fabs.f64 p)
(FPCore (p_m x)
 :precision binary64
 (if (<= p_m 2.2e-75) (/ p_m (- x)) (sqrt 0.5)))
p_m = fabs(p);
double code(double p_m, double x) {
	double tmp;
	if (p_m <= 2.2e-75) {
		tmp = p_m / -x;
	} else {
		tmp = sqrt(0.5);
	}
	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 (p_m <= 2.2d-75) then
        tmp = p_m / -x
    else
        tmp = sqrt(0.5d0)
    end if
    code = tmp
end function
p_m = Math.abs(p);
public static double code(double p_m, double x) {
	double tmp;
	if (p_m <= 2.2e-75) {
		tmp = p_m / -x;
	} else {
		tmp = Math.sqrt(0.5);
	}
	return tmp;
}
p_m = math.fabs(p)
def code(p_m, x):
	tmp = 0
	if p_m <= 2.2e-75:
		tmp = p_m / -x
	else:
		tmp = math.sqrt(0.5)
	return tmp
p_m = abs(p)
function code(p_m, x)
	tmp = 0.0
	if (p_m <= 2.2e-75)
		tmp = Float64(p_m / Float64(-x));
	else
		tmp = sqrt(0.5);
	end
	return tmp
end
p_m = abs(p);
function tmp_2 = code(p_m, x)
	tmp = 0.0;
	if (p_m <= 2.2e-75)
		tmp = p_m / -x;
	else
		tmp = sqrt(0.5);
	end
	tmp_2 = tmp;
end
p_m = N[Abs[p], $MachinePrecision]
code[p$95$m_, x_] := If[LessEqual[p$95$m, 2.2e-75], N[(p$95$m / (-x)), $MachinePrecision], N[Sqrt[0.5], $MachinePrecision]]
\begin{array}{l}
p_m = \left|p\right|

\\
\begin{array}{l}
\mathbf{if}\;p\_m \leq 2.2 \cdot 10^{-75}:\\
\;\;\;\;\frac{p\_m}{-x}\\

\mathbf{else}:\\
\;\;\;\;\sqrt{0.5}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if p < 2.20000000000000005e-75

    1. Initial program 72.6%

      \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
    2. Add Preprocessing
    3. Taylor expanded in x around -inf 15.3%

      \[\leadsto \color{blue}{-1 \cdot \frac{p \cdot \left(\sqrt{0.5} \cdot \sqrt{2}\right)}{x}} \]
    4. Step-by-step derivation
      1. mul-1-neg15.3%

        \[\leadsto \color{blue}{-\frac{p \cdot \left(\sqrt{0.5} \cdot \sqrt{2}\right)}{x}} \]
    5. Simplified15.3%

      \[\leadsto \color{blue}{-\frac{p \cdot \left(\sqrt{0.5} \cdot \sqrt{2}\right)}{x}} \]
    6. Step-by-step derivation
      1. sqrt-unprod15.4%

        \[\leadsto -\frac{p \cdot \color{blue}{\sqrt{0.5 \cdot 2}}}{x} \]
      2. metadata-eval15.4%

        \[\leadsto -\frac{p \cdot \sqrt{\color{blue}{1}}}{x} \]
      3. metadata-eval15.4%

        \[\leadsto -\frac{p \cdot \color{blue}{1}}{x} \]
    7. Applied egg-rr15.4%

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

    if 2.20000000000000005e-75 < p

    1. Initial program 93.0%

      \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
    2. Add Preprocessing
    3. Taylor expanded in x around 0 79.9%

      \[\leadsto \color{blue}{\sqrt{0.5}} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification36.1%

    \[\leadsto \begin{array}{l} \mathbf{if}\;p \leq 2.2 \cdot 10^{-75}:\\ \;\;\;\;\frac{p}{-x}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{0.5}\\ \end{array} \]
  5. Add Preprocessing

Alternative 4: 26.5% accurate, 53.8× speedup?

\[\begin{array}{l} p_m = \left|p\right| \\ \frac{p\_m}{-x} \end{array} \]
p_m = (fabs.f64 p)
(FPCore (p_m x) :precision binary64 (/ p_m (- x)))
p_m = fabs(p);
double code(double p_m, double x) {
	return p_m / -x;
}
p_m = abs(p)
real(8) function code(p_m, x)
    real(8), intent (in) :: p_m
    real(8), intent (in) :: x
    code = p_m / -x
end function
p_m = Math.abs(p);
public static double code(double p_m, double x) {
	return p_m / -x;
}
p_m = math.fabs(p)
def code(p_m, x):
	return p_m / -x
p_m = abs(p)
function code(p_m, x)
	return Float64(p_m / Float64(-x))
end
p_m = abs(p);
function tmp = code(p_m, x)
	tmp = p_m / -x;
end
p_m = N[Abs[p], $MachinePrecision]
code[p$95$m_, x_] := N[(p$95$m / (-x)), $MachinePrecision]
\begin{array}{l}
p_m = \left|p\right|

\\
\frac{p\_m}{-x}
\end{array}
Derivation
  1. Initial program 79.1%

    \[\sqrt{0.5 \cdot \left(1 + \frac{x}{\sqrt{\left(4 \cdot p\right) \cdot p + x \cdot x}}\right)} \]
  2. Add Preprocessing
  3. Taylor expanded in x around -inf 13.4%

    \[\leadsto \color{blue}{-1 \cdot \frac{p \cdot \left(\sqrt{0.5} \cdot \sqrt{2}\right)}{x}} \]
  4. Step-by-step derivation
    1. mul-1-neg13.4%

      \[\leadsto \color{blue}{-\frac{p \cdot \left(\sqrt{0.5} \cdot \sqrt{2}\right)}{x}} \]
  5. Simplified13.4%

    \[\leadsto \color{blue}{-\frac{p \cdot \left(\sqrt{0.5} \cdot \sqrt{2}\right)}{x}} \]
  6. Step-by-step derivation
    1. sqrt-unprod13.6%

      \[\leadsto -\frac{p \cdot \color{blue}{\sqrt{0.5 \cdot 2}}}{x} \]
    2. metadata-eval13.6%

      \[\leadsto -\frac{p \cdot \sqrt{\color{blue}{1}}}{x} \]
    3. metadata-eval13.6%

      \[\leadsto -\frac{p \cdot \color{blue}{1}}{x} \]
  7. Applied egg-rr13.6%

    \[\leadsto -\frac{p \cdot \color{blue}{1}}{x} \]
  8. Final simplification13.6%

    \[\leadsto \frac{p}{-x} \]
  9. Add Preprocessing

Developer target: 79.6% 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 2024076 
(FPCore (p x)
  :name "Given's Rotation SVD example"
  :precision binary64
  :pre (and (< 1e-150 (fabs x)) (< (fabs x) 1e+150))

  :alt
  (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))))))))