Linear.Quaternion:$clog from linear-1.19.1.3

Percentage Accurate: 69.1% → 99.8%
Time: 1.9s
Alternatives: 3
Speedup: 1.3×

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));
}
module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(8) function code(x, y)
use fmin_fmax_functions
    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}

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 3 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: 69.1% 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));
}
module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(8) function code(x, y)
use fmin_fmax_functions
    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: 99.8% accurate, 0.7× speedup?

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} \mathbf{if}\;x\_m \leq 4.5 \cdot 10^{+123}:\\ \;\;\;\;\sqrt{\mathsf{fma}\left(x\_m, x\_m, y\right)}\\ \mathbf{else}:\\ \;\;\;\;x\_m\\ \end{array} \end{array} \]
x_m = (fabs.f64 x)
(FPCore (x_m y)
 :precision binary64
 (if (<= x_m 4.5e+123) (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 <= 4.5e+123) {
		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 (x_m <= 4.5e+123)
		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[x$95$m, 4.5e+123], 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 \leq 4.5 \cdot 10^{+123}:\\
\;\;\;\;\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 x < 4.49999999999999983e123

    1. Initial program 69.1%

      \[\sqrt{x \cdot x + y} \]
    2. Step-by-step derivation
      1. lift-*.f64N/A

        \[\leadsto \sqrt{\color{blue}{x \cdot x} + y} \]
      2. lift-+.f64N/A

        \[\leadsto \sqrt{\color{blue}{x \cdot x + y}} \]
      3. pow2N/A

        \[\leadsto \sqrt{\color{blue}{{x}^{2}} + y} \]
      4. rem-square-sqrtN/A

        \[\leadsto \sqrt{\color{blue}{\sqrt{{x}^{2}} \cdot \sqrt{{x}^{2}}} + y} \]
      5. lower-fma.f64N/A

        \[\leadsto \sqrt{\color{blue}{\mathsf{fma}\left(\sqrt{{x}^{2}}, \sqrt{{x}^{2}}, y\right)}} \]
      6. pow1/2N/A

        \[\leadsto \sqrt{\mathsf{fma}\left(\color{blue}{{\left({x}^{2}\right)}^{\frac{1}{2}}}, \sqrt{{x}^{2}}, y\right)} \]
      7. pow2N/A

        \[\leadsto \sqrt{\mathsf{fma}\left({\color{blue}{\left(x \cdot x\right)}}^{\frac{1}{2}}, \sqrt{{x}^{2}}, y\right)} \]
      8. unpow-prod-downN/A

        \[\leadsto \sqrt{\mathsf{fma}\left(\color{blue}{{x}^{\frac{1}{2}} \cdot {x}^{\frac{1}{2}}}, \sqrt{{x}^{2}}, y\right)} \]
      9. metadata-evalN/A

        \[\leadsto \sqrt{\mathsf{fma}\left({x}^{\color{blue}{\left(\frac{1}{2}\right)}} \cdot {x}^{\frac{1}{2}}, \sqrt{{x}^{2}}, y\right)} \]
      10. metadata-evalN/A

        \[\leadsto \sqrt{\mathsf{fma}\left({x}^{\left(\frac{1}{2}\right)} \cdot {x}^{\color{blue}{\left(\frac{1}{2}\right)}}, \sqrt{{x}^{2}}, y\right)} \]
      11. sqr-powN/A

        \[\leadsto \sqrt{\mathsf{fma}\left(\color{blue}{{x}^{1}}, \sqrt{{x}^{2}}, y\right)} \]
      12. unpow1N/A

        \[\leadsto \sqrt{\mathsf{fma}\left(\color{blue}{x}, \sqrt{{x}^{2}}, y\right)} \]
      13. pow1/2N/A

        \[\leadsto \sqrt{\mathsf{fma}\left(x, \color{blue}{{\left({x}^{2}\right)}^{\frac{1}{2}}}, y\right)} \]
      14. pow2N/A

        \[\leadsto \sqrt{\mathsf{fma}\left(x, {\color{blue}{\left(x \cdot x\right)}}^{\frac{1}{2}}, y\right)} \]
      15. unpow-prod-downN/A

        \[\leadsto \sqrt{\mathsf{fma}\left(x, \color{blue}{{x}^{\frac{1}{2}} \cdot {x}^{\frac{1}{2}}}, y\right)} \]
      16. metadata-evalN/A

        \[\leadsto \sqrt{\mathsf{fma}\left(x, {x}^{\color{blue}{\left(\frac{1}{2}\right)}} \cdot {x}^{\frac{1}{2}}, y\right)} \]
      17. metadata-evalN/A

        \[\leadsto \sqrt{\mathsf{fma}\left(x, {x}^{\left(\frac{1}{2}\right)} \cdot {x}^{\color{blue}{\left(\frac{1}{2}\right)}}, y\right)} \]
      18. sqr-powN/A

        \[\leadsto \sqrt{\mathsf{fma}\left(x, \color{blue}{{x}^{1}}, y\right)} \]
      19. unpow169.1

        \[\leadsto \sqrt{\mathsf{fma}\left(x, \color{blue}{x}, y\right)} \]
    3. Applied rewrites69.1%

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

    if 4.49999999999999983e123 < x

    1. Initial program 69.1%

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

      \[\leadsto \color{blue}{\sqrt{{x}^{2}}} \]
    3. Step-by-step derivation
      1. pow1/2N/A

        \[\leadsto {\left({x}^{2}\right)}^{\color{blue}{\frac{1}{2}}} \]
      2. pow2N/A

        \[\leadsto {\left(x \cdot x\right)}^{\frac{1}{2}} \]
      3. unpow-prod-downN/A

        \[\leadsto {x}^{\frac{1}{2}} \cdot \color{blue}{{x}^{\frac{1}{2}}} \]
      4. metadata-evalN/A

        \[\leadsto {x}^{\left(\frac{1}{2}\right)} \cdot {x}^{\frac{1}{2}} \]
      5. metadata-evalN/A

        \[\leadsto {x}^{\left(\frac{1}{2}\right)} \cdot {x}^{\left(\frac{1}{\color{blue}{2}}\right)} \]
      6. sqr-powN/A

        \[\leadsto {x}^{\color{blue}{1}} \]
      7. unpow168.0

        \[\leadsto x \]
    4. Applied rewrites68.0%

      \[\leadsto \color{blue}{x} \]
  3. Recombined 2 regimes into one program.
  4. Add Preprocessing

Alternative 2: 86.8% accurate, 1.3× speedup?

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} \mathbf{if}\;x\_m \leq 10^{-117}:\\ \;\;\;\;\sqrt{y}\\ \mathbf{else}:\\ \;\;\;\;x\_m\\ \end{array} \end{array} \]
x_m = (fabs.f64 x)
(FPCore (x_m y) :precision binary64 (if (<= x_m 1e-117) (sqrt y) x_m))
x_m = fabs(x);
double code(double x_m, double y) {
	double tmp;
	if (x_m <= 1e-117) {
		tmp = sqrt(y);
	} else {
		tmp = x_m;
	}
	return tmp;
}
x_m =     private
module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(8) function code(x_m, y)
use fmin_fmax_functions
    real(8), intent (in) :: x_m
    real(8), intent (in) :: y
    real(8) :: tmp
    if (x_m <= 1d-117) then
        tmp = sqrt(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 <= 1e-117) {
		tmp = Math.sqrt(y);
	} else {
		tmp = x_m;
	}
	return tmp;
}
x_m = math.fabs(x)
def code(x_m, y):
	tmp = 0
	if x_m <= 1e-117:
		tmp = math.sqrt(y)
	else:
		tmp = x_m
	return tmp
x_m = abs(x)
function code(x_m, y)
	tmp = 0.0
	if (x_m <= 1e-117)
		tmp = sqrt(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 <= 1e-117)
		tmp = sqrt(y);
	else
		tmp = x_m;
	end
	tmp_2 = tmp;
end
x_m = N[Abs[x], $MachinePrecision]
code[x$95$m_, y_] := If[LessEqual[x$95$m, 1e-117], N[Sqrt[y], $MachinePrecision], x$95$m]
\begin{array}{l}
x_m = \left|x\right|

\\
\begin{array}{l}
\mathbf{if}\;x\_m \leq 10^{-117}:\\
\;\;\;\;\sqrt{y}\\

\mathbf{else}:\\
\;\;\;\;x\_m\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < 1.00000000000000003e-117

    1. Initial program 69.1%

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

      \[\leadsto \sqrt{\color{blue}{y}} \]
    3. Step-by-step derivation
      1. Applied rewrites34.4%

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

      if 1.00000000000000003e-117 < x

      1. Initial program 69.1%

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

        \[\leadsto \color{blue}{\sqrt{{x}^{2}}} \]
      3. Step-by-step derivation
        1. pow1/2N/A

          \[\leadsto {\left({x}^{2}\right)}^{\color{blue}{\frac{1}{2}}} \]
        2. pow2N/A

          \[\leadsto {\left(x \cdot x\right)}^{\frac{1}{2}} \]
        3. unpow-prod-downN/A

          \[\leadsto {x}^{\frac{1}{2}} \cdot \color{blue}{{x}^{\frac{1}{2}}} \]
        4. metadata-evalN/A

          \[\leadsto {x}^{\left(\frac{1}{2}\right)} \cdot {x}^{\frac{1}{2}} \]
        5. metadata-evalN/A

          \[\leadsto {x}^{\left(\frac{1}{2}\right)} \cdot {x}^{\left(\frac{1}{\color{blue}{2}}\right)} \]
        6. sqr-powN/A

          \[\leadsto {x}^{\color{blue}{1}} \]
        7. unpow168.0

          \[\leadsto x \]
      4. Applied rewrites68.0%

        \[\leadsto \color{blue}{x} \]
    4. Recombined 2 regimes into one program.
    5. Add Preprocessing

    Alternative 3: 68.0% accurate, 8.5× 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 =     private
    module fmin_fmax_functions
        implicit none
        private
        public fmax
        public fmin
    
        interface fmax
            module procedure fmax88
            module procedure fmax44
            module procedure fmax84
            module procedure fmax48
        end interface
        interface fmin
            module procedure fmin88
            module procedure fmin44
            module procedure fmin84
            module procedure fmin48
        end interface
    contains
        real(8) function fmax88(x, y) result (res)
            real(8), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(x, max(x, y), y /= y), x /= x)
        end function
        real(4) function fmax44(x, y) result (res)
            real(4), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(y, merge(x, max(x, y), y /= y), x /= x)
        end function
        real(8) function fmax84(x, y) result(res)
            real(8), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
        end function
        real(8) function fmax48(x, y) result(res)
            real(4), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
        end function
        real(8) function fmin88(x, y) result (res)
            real(8), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(x, min(x, y), y /= y), x /= x)
        end function
        real(4) function fmin44(x, y) result (res)
            real(4), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(y, merge(x, min(x, y), y /= y), x /= x)
        end function
        real(8) function fmin84(x, y) result(res)
            real(8), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
        end function
        real(8) function fmin48(x, y) result(res)
            real(4), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
        end function
    end module
    
    real(8) function code(x_m, y)
    use fmin_fmax_functions
        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 69.1%

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

      \[\leadsto \color{blue}{\sqrt{{x}^{2}}} \]
    3. Step-by-step derivation
      1. pow1/2N/A

        \[\leadsto {\left({x}^{2}\right)}^{\color{blue}{\frac{1}{2}}} \]
      2. pow2N/A

        \[\leadsto {\left(x \cdot x\right)}^{\frac{1}{2}} \]
      3. unpow-prod-downN/A

        \[\leadsto {x}^{\frac{1}{2}} \cdot \color{blue}{{x}^{\frac{1}{2}}} \]
      4. metadata-evalN/A

        \[\leadsto {x}^{\left(\frac{1}{2}\right)} \cdot {x}^{\frac{1}{2}} \]
      5. metadata-evalN/A

        \[\leadsto {x}^{\left(\frac{1}{2}\right)} \cdot {x}^{\left(\frac{1}{\color{blue}{2}}\right)} \]
      6. sqr-powN/A

        \[\leadsto {x}^{\color{blue}{1}} \]
      7. unpow168.0

        \[\leadsto x \]
    4. Applied rewrites68.0%

      \[\leadsto \color{blue}{x} \]
    5. Add Preprocessing

    Reproduce

    ?
    herbie shell --seed 2025138 
    (FPCore (x y)
      :name "Linear.Quaternion:$clog from linear-1.19.1.3"
      :precision binary64
      (sqrt (+ (* x x) y)))