Linear.Quaternion:$clog from linear-1.19.1.3

Percentage Accurate: 70.3% → 99.8%
Time: 4.5s
Alternatives: 4
Speedup: 0.9×

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 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: 70.3% 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: 99.8% accurate, 0.6× speedup?

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} \mathbf{if}\;x\_m \cdot x\_m \leq 10^{+259}:\\ \;\;\;\;\sqrt{x\_m \cdot x\_m + y}\\ \mathbf{else}:\\ \;\;\;\;x\_m\\ \end{array} \end{array} \]
x_m = (fabs.f64 x)
(FPCore (x_m y)
 :precision binary64
 (if (<= (* x_m x_m) 1e+259) (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+259) {
		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+259) 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+259) {
		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+259:
		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+259)
		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+259)
		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+259], 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^{+259}:\\
\;\;\;\;\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) < 9.999999999999999e258

    1. Initial program 100.0%

      \[\sqrt{x \cdot x + y} \]
    2. Add Preprocessing

    if 9.999999999999999e258 < (*.f64 x x)

    1. Initial program 16.3%

      \[\sqrt{x \cdot x + y} \]
    2. Add Preprocessing
    3. Taylor expanded in x around inf

      \[\leadsto \color{blue}{x} \]
    4. Step-by-step derivation
      1. Simplified50.7%

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

    Alternative 2: 99.8% accurate, 0.7× speedup?

    \[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} \mathbf{if}\;x\_m \cdot x\_m \leq 10^{+259}:\\ \;\;\;\;\sqrt{\mathsf{fma}\left(x\_m, x\_m, y\right)}\\ \mathbf{else}:\\ \;\;\;\;x\_m\\ \end{array} \end{array} \]
    x_m = (fabs.f64 x)
    (FPCore (x_m y)
     :precision binary64
     (if (<= (* x_m x_m) 1e+259) (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+259) {
    		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+259)
    		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+259], 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^{+259}:\\
    \;\;\;\;\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) < 9.999999999999999e258

      1. Initial program 100.0%

        \[\sqrt{x \cdot x + y} \]
      2. Add Preprocessing
      3. Step-by-step derivation
        1. accelerator-lowering-fma.f64100.0

          \[\leadsto \sqrt{\color{blue}{\mathsf{fma}\left(x, x, y\right)}} \]
      4. Applied egg-rr100.0%

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

      if 9.999999999999999e258 < (*.f64 x x)

      1. Initial program 16.3%

        \[\sqrt{x \cdot x + y} \]
      2. Add Preprocessing
      3. Taylor expanded in x around inf

        \[\leadsto \color{blue}{x} \]
      4. Step-by-step derivation
        1. Simplified50.7%

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

      Alternative 3: 88.6% accurate, 0.9× speedup?

      \[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} \mathbf{if}\;x\_m \cdot x\_m \leq 2 \cdot 10^{-135}:\\ \;\;\;\;\sqrt{y}\\ \mathbf{else}:\\ \;\;\;\;x\_m\\ \end{array} \end{array} \]
      x_m = (fabs.f64 x)
      (FPCore (x_m y) :precision binary64 (if (<= (* x_m x_m) 2e-135) (sqrt y) x_m))
      x_m = fabs(x);
      double code(double x_m, double y) {
      	double tmp;
      	if ((x_m * x_m) <= 2e-135) {
      		tmp = sqrt(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) <= 2d-135) 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 * x_m) <= 2e-135) {
      		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 * x_m) <= 2e-135:
      		tmp = math.sqrt(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) <= 2e-135)
      		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 * x_m) <= 2e-135)
      		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[N[(x$95$m * x$95$m), $MachinePrecision], 2e-135], N[Sqrt[y], $MachinePrecision], x$95$m]
      
      \begin{array}{l}
      x_m = \left|x\right|
      
      \\
      \begin{array}{l}
      \mathbf{if}\;x\_m \cdot x\_m \leq 2 \cdot 10^{-135}:\\
      \;\;\;\;\sqrt{y}\\
      
      \mathbf{else}:\\
      \;\;\;\;x\_m\\
      
      
      \end{array}
      \end{array}
      
      Derivation
      1. Split input into 2 regimes
      2. if (*.f64 x x) < 2.0000000000000001e-135

        1. Initial program 100.0%

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

          \[\leadsto \sqrt{\color{blue}{y}} \]
        4. Step-by-step derivation
          1. Simplified93.2%

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

          if 2.0000000000000001e-135 < (*.f64 x x)

          1. Initial program 57.7%

            \[\sqrt{x \cdot x + y} \]
          2. Add Preprocessing
          3. Taylor expanded in x around inf

            \[\leadsto \color{blue}{x} \]
          4. Step-by-step derivation
            1. Simplified43.5%

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

          Alternative 4: 66.9% accurate, 19.0× 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 69.6%

            \[\sqrt{x \cdot x + y} \]
          2. Add Preprocessing
          3. Taylor expanded in x around inf

            \[\leadsto \color{blue}{x} \]
          4. Step-by-step derivation
            1. Simplified33.8%

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

            Developer Target 1: 98.5% accurate, 0.6× 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 2024204 
            (FPCore (x y)
              :name "Linear.Quaternion:$clog from linear-1.19.1.3"
              :precision binary64
            
              :alt
              (! :herbie-platform default (if (< x -1509769801047259300000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000) (- (+ (* 1/2 (/ y x)) x)) (if (< x 5582399551122541000000000000000000000000000000000000000000) (sqrt (+ (* x x) y)) (+ (* 1/2 (/ y x)) x))))
            
              (sqrt (+ (* x x) y)))