Linear.Quaternion:$clog from linear-1.19.1.3

Percentage Accurate: 68.7% → 99.7%
Time: 4.1s
Alternatives: 5
Speedup: 1.0×

Specification

?
\[\begin{array}{l} \\ \sqrt{x \cdot x + y} \end{array} \]
(FPCore (x y) :precision binary64 (sqrt (+ (* x x) y)))
double code(double x, double y) {
	return sqrt(((x * x) + y));
}
real(8) function code(x, y)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    code = sqrt(((x * x) + y))
end function
public static double code(double x, double y) {
	return Math.sqrt(((x * x) + y));
}
def code(x, y):
	return math.sqrt(((x * x) + y))
function code(x, y)
	return sqrt(Float64(Float64(x * x) + y))
end
function tmp = code(x, y)
	tmp = sqrt(((x * x) + y));
end
code[x_, y_] := N[Sqrt[N[(N[(x * x), $MachinePrecision] + y), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\sqrt{x \cdot x + y}
\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 5 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: 68.7% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \sqrt{x \cdot x + y} \end{array} \]
(FPCore (x y) :precision binary64 (sqrt (+ (* x x) y)))
double code(double x, double y) {
	return sqrt(((x * x) + y));
}
real(8) function code(x, y)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    code = sqrt(((x * x) + y))
end function
public static double code(double x, double y) {
	return Math.sqrt(((x * x) + y));
}
def code(x, y):
	return math.sqrt(((x * x) + y))
function code(x, y)
	return sqrt(Float64(Float64(x * x) + y))
end
function tmp = code(x, y)
	tmp = sqrt(((x * x) + y));
end
code[x_, y_] := N[Sqrt[N[(N[(x * x), $MachinePrecision] + y), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\sqrt{x \cdot x + y}
\end{array}

Alternative 1: 99.7% accurate, 0.5× speedup?

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} \mathbf{if}\;x_m \cdot x_m \leq 10^{+228}:\\ \;\;\;\;\sqrt{\mathsf{fma}\left(x_m, x_m, y\right)}\\ \mathbf{else}:\\ \;\;\;\;x_m\\ \end{array} \end{array} \]
x_m = (fabs.f64 x)
(FPCore (x_m y)
 :precision binary64
 (if (<= (* x_m x_m) 1e+228) (sqrt (fma x_m x_m y)) x_m))
x_m = fabs(x);
double code(double x_m, double y) {
	double tmp;
	if ((x_m * x_m) <= 1e+228) {
		tmp = sqrt(fma(x_m, x_m, y));
	} else {
		tmp = x_m;
	}
	return tmp;
}
x_m = abs(x)
function code(x_m, y)
	tmp = 0.0
	if (Float64(x_m * x_m) <= 1e+228)
		tmp = sqrt(fma(x_m, x_m, y));
	else
		tmp = x_m;
	end
	return tmp
end
x_m = N[Abs[x], $MachinePrecision]
code[x$95$m_, y_] := If[LessEqual[N[(x$95$m * x$95$m), $MachinePrecision], 1e+228], N[Sqrt[N[(x$95$m * x$95$m + y), $MachinePrecision]], $MachinePrecision], x$95$m]
\begin{array}{l}
x_m = \left|x\right|

\\
\begin{array}{l}
\mathbf{if}\;x_m \cdot x_m \leq 10^{+228}:\\
\;\;\;\;\sqrt{\mathsf{fma}\left(x_m, x_m, y\right)}\\

\mathbf{else}:\\
\;\;\;\;x_m\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (*.f64 x x) < 9.9999999999999992e227

    1. Initial program 100.0%

      \[\sqrt{x \cdot x + y} \]
    2. Step-by-step derivation
      1. fma-def100.0%

        \[\leadsto \sqrt{\color{blue}{\mathsf{fma}\left(x, x, y\right)}} \]
    3. Simplified100.0%

      \[\leadsto \color{blue}{\sqrt{\mathsf{fma}\left(x, x, y\right)}} \]

    if 9.9999999999999992e227 < (*.f64 x x)

    1. Initial program 20.3%

      \[\sqrt{x \cdot x + y} \]
    2. Taylor expanded in x around inf 48.7%

      \[\leadsto \color{blue}{x} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification80.1%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \cdot x \leq 10^{+228}:\\ \;\;\;\;\sqrt{\mathsf{fma}\left(x, x, y\right)}\\ \mathbf{else}:\\ \;\;\;\;x\\ \end{array} \]

Alternative 2: 99.7% accurate, 1.0× speedup?

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} \mathbf{if}\;x_m \cdot x_m \leq 10^{+228}:\\ \;\;\;\;\sqrt{x_m \cdot x_m + y}\\ \mathbf{else}:\\ \;\;\;\;x_m\\ \end{array} \end{array} \]
x_m = (fabs.f64 x)
(FPCore (x_m y)
 :precision binary64
 (if (<= (* x_m x_m) 1e+228) (sqrt (+ (* x_m x_m) y)) x_m))
x_m = fabs(x);
double code(double x_m, double y) {
	double tmp;
	if ((x_m * x_m) <= 1e+228) {
		tmp = sqrt(((x_m * x_m) + y));
	} else {
		tmp = x_m;
	}
	return tmp;
}
x_m = abs(x)
real(8) function code(x_m, y)
    real(8), intent (in) :: x_m
    real(8), intent (in) :: y
    real(8) :: tmp
    if ((x_m * x_m) <= 1d+228) then
        tmp = sqrt(((x_m * x_m) + y))
    else
        tmp = x_m
    end if
    code = tmp
end function
x_m = Math.abs(x);
public static double code(double x_m, double y) {
	double tmp;
	if ((x_m * x_m) <= 1e+228) {
		tmp = Math.sqrt(((x_m * x_m) + y));
	} else {
		tmp = x_m;
	}
	return tmp;
}
x_m = math.fabs(x)
def code(x_m, y):
	tmp = 0
	if (x_m * x_m) <= 1e+228:
		tmp = math.sqrt(((x_m * x_m) + y))
	else:
		tmp = x_m
	return tmp
x_m = abs(x)
function code(x_m, y)
	tmp = 0.0
	if (Float64(x_m * x_m) <= 1e+228)
		tmp = sqrt(Float64(Float64(x_m * x_m) + y));
	else
		tmp = x_m;
	end
	return tmp
end
x_m = abs(x);
function tmp_2 = code(x_m, y)
	tmp = 0.0;
	if ((x_m * x_m) <= 1e+228)
		tmp = sqrt(((x_m * x_m) + y));
	else
		tmp = x_m;
	end
	tmp_2 = tmp;
end
x_m = N[Abs[x], $MachinePrecision]
code[x$95$m_, y_] := If[LessEqual[N[(x$95$m * x$95$m), $MachinePrecision], 1e+228], N[Sqrt[N[(N[(x$95$m * x$95$m), $MachinePrecision] + y), $MachinePrecision]], $MachinePrecision], x$95$m]
\begin{array}{l}
x_m = \left|x\right|

\\
\begin{array}{l}
\mathbf{if}\;x_m \cdot x_m \leq 10^{+228}:\\
\;\;\;\;\sqrt{x_m \cdot x_m + y}\\

\mathbf{else}:\\
\;\;\;\;x_m\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (*.f64 x x) < 9.9999999999999992e227

    1. Initial program 100.0%

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

    if 9.9999999999999992e227 < (*.f64 x x)

    1. Initial program 20.3%

      \[\sqrt{x \cdot x + y} \]
    2. Taylor expanded in x around inf 48.7%

      \[\leadsto \color{blue}{x} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification80.1%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \cdot x \leq 10^{+228}:\\ \;\;\;\;\sqrt{x \cdot x + y}\\ \mathbf{else}:\\ \;\;\;\;x\\ \end{array} \]

Alternative 3: 89.6% accurate, 1.0× speedup?

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} \mathbf{if}\;x_m \leq 2 \cdot 10^{-35}:\\ \;\;\;\;\sqrt{y}\\ \mathbf{else}:\\ \;\;\;\;x_m + y \cdot \frac{0.5}{x_m}\\ \end{array} \end{array} \]
x_m = (fabs.f64 x)
(FPCore (x_m y)
 :precision binary64
 (if (<= x_m 2e-35) (sqrt y) (+ x_m (* y (/ 0.5 x_m)))))
x_m = fabs(x);
double code(double x_m, double y) {
	double tmp;
	if (x_m <= 2e-35) {
		tmp = sqrt(y);
	} else {
		tmp = x_m + (y * (0.5 / x_m));
	}
	return tmp;
}
x_m = abs(x)
real(8) function code(x_m, y)
    real(8), intent (in) :: x_m
    real(8), intent (in) :: y
    real(8) :: tmp
    if (x_m <= 2d-35) then
        tmp = sqrt(y)
    else
        tmp = x_m + (y * (0.5d0 / x_m))
    end if
    code = tmp
end function
x_m = Math.abs(x);
public static double code(double x_m, double y) {
	double tmp;
	if (x_m <= 2e-35) {
		tmp = Math.sqrt(y);
	} else {
		tmp = x_m + (y * (0.5 / x_m));
	}
	return tmp;
}
x_m = math.fabs(x)
def code(x_m, y):
	tmp = 0
	if x_m <= 2e-35:
		tmp = math.sqrt(y)
	else:
		tmp = x_m + (y * (0.5 / x_m))
	return tmp
x_m = abs(x)
function code(x_m, y)
	tmp = 0.0
	if (x_m <= 2e-35)
		tmp = sqrt(y);
	else
		tmp = Float64(x_m + Float64(y * Float64(0.5 / x_m)));
	end
	return tmp
end
x_m = abs(x);
function tmp_2 = code(x_m, y)
	tmp = 0.0;
	if (x_m <= 2e-35)
		tmp = sqrt(y);
	else
		tmp = x_m + (y * (0.5 / x_m));
	end
	tmp_2 = tmp;
end
x_m = N[Abs[x], $MachinePrecision]
code[x$95$m_, y_] := If[LessEqual[x$95$m, 2e-35], N[Sqrt[y], $MachinePrecision], N[(x$95$m + N[(y * N[(0.5 / x$95$m), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
x_m = \left|x\right|

\\
\begin{array}{l}
\mathbf{if}\;x_m \leq 2 \cdot 10^{-35}:\\
\;\;\;\;\sqrt{y}\\

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


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < 2.00000000000000002e-35

    1. Initial program 77.4%

      \[\sqrt{x \cdot x + y} \]
    2. Taylor expanded in x around 0 48.4%

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

    if 2.00000000000000002e-35 < x

    1. Initial program 52.4%

      \[\sqrt{x \cdot x + y} \]
    2. Taylor expanded in x around inf 77.5%

      \[\leadsto \color{blue}{x + \left(-0.125 \cdot \frac{{y}^{2}}{{x}^{3}} + 0.5 \cdot \frac{y}{x}\right)} \]
    3. Taylor expanded in y around 0 89.0%

      \[\leadsto x + \color{blue}{0.5 \cdot \frac{y}{x}} \]
    4. Step-by-step derivation
      1. associate-*r/89.0%

        \[\leadsto x + \color{blue}{\frac{0.5 \cdot y}{x}} \]
      2. associate-/l*89.0%

        \[\leadsto x + \color{blue}{\frac{0.5}{\frac{x}{y}}} \]
    5. Simplified89.0%

      \[\leadsto x + \color{blue}{\frac{0.5}{\frac{x}{y}}} \]
    6. Step-by-step derivation
      1. associate-/r/89.0%

        \[\leadsto x + \color{blue}{\frac{0.5}{x} \cdot y} \]
    7. Applied egg-rr89.0%

      \[\leadsto x + \color{blue}{\frac{0.5}{x} \cdot y} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification61.7%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq 2 \cdot 10^{-35}:\\ \;\;\;\;\sqrt{y}\\ \mathbf{else}:\\ \;\;\;\;x + y \cdot \frac{0.5}{x}\\ \end{array} \]

Alternative 4: 68.3% accurate, 15.0× speedup?

\[\begin{array}{l} x_m = \left|x\right| \\ x_m + y \cdot \frac{0.5}{x_m} \end{array} \]
x_m = (fabs.f64 x)
(FPCore (x_m y) :precision binary64 (+ x_m (* y (/ 0.5 x_m))))
x_m = fabs(x);
double code(double x_m, double y) {
	return x_m + (y * (0.5 / x_m));
}
x_m = abs(x)
real(8) function code(x_m, y)
    real(8), intent (in) :: x_m
    real(8), intent (in) :: y
    code = x_m + (y * (0.5d0 / x_m))
end function
x_m = Math.abs(x);
public static double code(double x_m, double y) {
	return x_m + (y * (0.5 / x_m));
}
x_m = math.fabs(x)
def code(x_m, y):
	return x_m + (y * (0.5 / x_m))
x_m = abs(x)
function code(x_m, y)
	return Float64(x_m + Float64(y * Float64(0.5 / x_m)))
end
x_m = abs(x);
function tmp = code(x_m, y)
	tmp = x_m + (y * (0.5 / x_m));
end
x_m = N[Abs[x], $MachinePrecision]
code[x$95$m_, y_] := N[(x$95$m + N[(y * N[(0.5 / x$95$m), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
x_m = \left|x\right|

\\
x_m + y \cdot \frac{0.5}{x_m}
\end{array}
Derivation
  1. Initial program 69.2%

    \[\sqrt{x \cdot x + y} \]
  2. Taylor expanded in x around inf 26.4%

    \[\leadsto \color{blue}{x + \left(-0.125 \cdot \frac{{y}^{2}}{{x}^{3}} + 0.5 \cdot \frac{y}{x}\right)} \]
  3. Taylor expanded in y around 0 30.8%

    \[\leadsto x + \color{blue}{0.5 \cdot \frac{y}{x}} \]
  4. Step-by-step derivation
    1. associate-*r/30.8%

      \[\leadsto x + \color{blue}{\frac{0.5 \cdot y}{x}} \]
    2. associate-/l*30.8%

      \[\leadsto x + \color{blue}{\frac{0.5}{\frac{x}{y}}} \]
  5. Simplified30.8%

    \[\leadsto x + \color{blue}{\frac{0.5}{\frac{x}{y}}} \]
  6. Step-by-step derivation
    1. associate-/r/30.8%

      \[\leadsto x + \color{blue}{\frac{0.5}{x} \cdot y} \]
  7. Applied egg-rr30.8%

    \[\leadsto x + \color{blue}{\frac{0.5}{x} \cdot y} \]
  8. Final simplification30.8%

    \[\leadsto x + y \cdot \frac{0.5}{x} \]

Alternative 5: 67.8% accurate, 105.0× speedup?

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

\\
x_m
\end{array}
Derivation
  1. Initial program 69.2%

    \[\sqrt{x \cdot x + y} \]
  2. Taylor expanded in x around inf 31.0%

    \[\leadsto \color{blue}{x} \]
  3. Final simplification31.0%

    \[\leadsto x \]

Developer target: 98.5% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := 0.5 \cdot \frac{y}{x} + x\\ \mathbf{if}\;x < -1.5097698010472593 \cdot 10^{+153}:\\ \;\;\;\;-t_0\\ \mathbf{elif}\;x < 5.582399551122541 \cdot 10^{+57}:\\ \;\;\;\;\sqrt{x \cdot x + y}\\ \mathbf{else}:\\ \;\;\;\;t_0\\ \end{array} \end{array} \]
(FPCore (x y)
 :precision binary64
 (let* ((t_0 (+ (* 0.5 (/ y x)) x)))
   (if (< x -1.5097698010472593e+153)
     (- t_0)
     (if (< x 5.582399551122541e+57) (sqrt (+ (* x x) y)) t_0))))
double code(double x, double y) {
	double t_0 = (0.5 * (y / x)) + x;
	double tmp;
	if (x < -1.5097698010472593e+153) {
		tmp = -t_0;
	} else if (x < 5.582399551122541e+57) {
		tmp = sqrt(((x * x) + y));
	} else {
		tmp = t_0;
	}
	return tmp;
}
real(8) function code(x, y)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8) :: t_0
    real(8) :: tmp
    t_0 = (0.5d0 * (y / x)) + x
    if (x < (-1.5097698010472593d+153)) then
        tmp = -t_0
    else if (x < 5.582399551122541d+57) then
        tmp = sqrt(((x * x) + y))
    else
        tmp = t_0
    end if
    code = tmp
end function
public static double code(double x, double y) {
	double t_0 = (0.5 * (y / x)) + x;
	double tmp;
	if (x < -1.5097698010472593e+153) {
		tmp = -t_0;
	} else if (x < 5.582399551122541e+57) {
		tmp = Math.sqrt(((x * x) + y));
	} else {
		tmp = t_0;
	}
	return tmp;
}
def code(x, y):
	t_0 = (0.5 * (y / x)) + x
	tmp = 0
	if x < -1.5097698010472593e+153:
		tmp = -t_0
	elif x < 5.582399551122541e+57:
		tmp = math.sqrt(((x * x) + y))
	else:
		tmp = t_0
	return tmp
function code(x, y)
	t_0 = Float64(Float64(0.5 * Float64(y / x)) + x)
	tmp = 0.0
	if (x < -1.5097698010472593e+153)
		tmp = Float64(-t_0);
	elseif (x < 5.582399551122541e+57)
		tmp = sqrt(Float64(Float64(x * x) + y));
	else
		tmp = t_0;
	end
	return tmp
end
function tmp_2 = code(x, y)
	t_0 = (0.5 * (y / x)) + x;
	tmp = 0.0;
	if (x < -1.5097698010472593e+153)
		tmp = -t_0;
	elseif (x < 5.582399551122541e+57)
		tmp = sqrt(((x * x) + y));
	else
		tmp = t_0;
	end
	tmp_2 = tmp;
end
code[x_, y_] := Block[{t$95$0 = N[(N[(0.5 * N[(y / x), $MachinePrecision]), $MachinePrecision] + x), $MachinePrecision]}, If[Less[x, -1.5097698010472593e+153], (-t$95$0), If[Less[x, 5.582399551122541e+57], N[Sqrt[N[(N[(x * x), $MachinePrecision] + y), $MachinePrecision]], $MachinePrecision], t$95$0]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := 0.5 \cdot \frac{y}{x} + x\\
\mathbf{if}\;x < -1.5097698010472593 \cdot 10^{+153}:\\
\;\;\;\;-t_0\\

\mathbf{elif}\;x < 5.582399551122541 \cdot 10^{+57}:\\
\;\;\;\;\sqrt{x \cdot x + y}\\

\mathbf{else}:\\
\;\;\;\;t_0\\


\end{array}
\end{array}

Reproduce

?
herbie shell --seed 2023334 
(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)))