Hyperbolic arcsine

Percentage Accurate: 17.9% → 99.8%
Time: 5.7s
Alternatives: 3
Speedup: 20.3×

Specification

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

\\
\log \left(x + \sqrt{x \cdot x + 1}\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 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: 17.9% accurate, 1.0× speedup?

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

\\
\log \left(x + \sqrt{x \cdot x + 1}\right)
\end{array}

Alternative 1: 99.8% accurate, 1.2× speedup?

\[\begin{array}{l} \\ \sinh^{-1} x \end{array} \]
(FPCore (x) :precision binary64 (asinh x))
double code(double x) {
	return asinh(x);
}
def code(x):
	return math.asinh(x)
function code(x)
	return asinh(x)
end
function tmp = code(x)
	tmp = asinh(x);
end
code[x_] := N[ArcSinh[x], $MachinePrecision]
\begin{array}{l}

\\
\sinh^{-1} x
\end{array}
Derivation
  1. Initial program 15.9%

    \[\log \left(x + \sqrt{x \cdot x + 1}\right) \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-log.f64N/A

      \[\leadsto \color{blue}{\log \left(x + \sqrt{x \cdot x + 1}\right)} \]
    2. lift-+.f64N/A

      \[\leadsto \log \color{blue}{\left(x + \sqrt{x \cdot x + 1}\right)} \]
    3. lift-sqrt.f64N/A

      \[\leadsto \log \left(x + \color{blue}{\sqrt{x \cdot x + 1}}\right) \]
    4. lift-+.f64N/A

      \[\leadsto \log \left(x + \sqrt{\color{blue}{x \cdot x + 1}}\right) \]
    5. lift-*.f64N/A

      \[\leadsto \log \left(x + \sqrt{\color{blue}{x \cdot x} + 1}\right) \]
    6. asinh-def-revN/A

      \[\leadsto \color{blue}{\sinh^{-1} x} \]
    7. lower-asinh.f6499.8

      \[\leadsto \color{blue}{\sinh^{-1} x} \]
  4. Applied rewrites99.8%

    \[\leadsto \color{blue}{\sinh^{-1} x} \]
  5. Add Preprocessing

Alternative 2: 52.2% accurate, 20.3× speedup?

\[\begin{array}{l} \\ 1 \cdot x \end{array} \]
(FPCore (x) :precision binary64 (* 1.0 x))
double code(double x) {
	return 1.0 * x;
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = 1.0d0 * x
end function
public static double code(double x) {
	return 1.0 * x;
}
def code(x):
	return 1.0 * x
function code(x)
	return Float64(1.0 * x)
end
function tmp = code(x)
	tmp = 1.0 * x;
end
code[x_] := N[(1.0 * x), $MachinePrecision]
\begin{array}{l}

\\
1 \cdot x
\end{array}
Derivation
  1. Initial program 15.9%

    \[\log \left(x + \sqrt{x \cdot x + 1}\right) \]
  2. Add Preprocessing
  3. Taylor expanded in x around 0

    \[\leadsto \color{blue}{x \cdot \left(1 + \frac{-1}{6} \cdot {x}^{2}\right)} \]
  4. Step-by-step derivation
    1. distribute-rgt-inN/A

      \[\leadsto \color{blue}{1 \cdot x + \left(\frac{-1}{6} \cdot {x}^{2}\right) \cdot x} \]
    2. *-lft-identityN/A

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

      \[\leadsto \color{blue}{\left(\frac{-1}{6} \cdot {x}^{2}\right) \cdot x + x} \]
    4. associate-*l*N/A

      \[\leadsto \color{blue}{\frac{-1}{6} \cdot \left({x}^{2} \cdot x\right)} + x \]
    5. *-commutativeN/A

      \[\leadsto \color{blue}{\left({x}^{2} \cdot x\right) \cdot \frac{-1}{6}} + x \]
    6. lower-fma.f64N/A

      \[\leadsto \color{blue}{\mathsf{fma}\left({x}^{2} \cdot x, \frac{-1}{6}, x\right)} \]
    7. pow-plusN/A

      \[\leadsto \mathsf{fma}\left(\color{blue}{{x}^{\left(2 + 1\right)}}, \frac{-1}{6}, x\right) \]
    8. lower-pow.f64N/A

      \[\leadsto \mathsf{fma}\left(\color{blue}{{x}^{\left(2 + 1\right)}}, \frac{-1}{6}, x\right) \]
    9. metadata-eval49.1

      \[\leadsto \mathsf{fma}\left({x}^{\color{blue}{3}}, -0.16666666666666666, x\right) \]
  5. Applied rewrites49.1%

    \[\leadsto \color{blue}{\mathsf{fma}\left({x}^{3}, -0.16666666666666666, x\right)} \]
  6. Step-by-step derivation
    1. Applied rewrites49.1%

      \[\leadsto \mathsf{fma}\left(-0.16666666666666666 \cdot x, x, 1\right) \cdot \color{blue}{x} \]
    2. Taylor expanded in x around 0

      \[\leadsto 1 \cdot x \]
    3. Step-by-step derivation
      1. Applied rewrites50.9%

        \[\leadsto 1 \cdot x \]
      2. Add Preprocessing

      Alternative 3: 2.4% accurate, 40.7× speedup?

      \[\begin{array}{l} \\ -x \end{array} \]
      (FPCore (x) :precision binary64 (- x))
      double code(double x) {
      	return -x;
      }
      
      real(8) function code(x)
          real(8), intent (in) :: x
          code = -x
      end function
      
      public static double code(double x) {
      	return -x;
      }
      
      def code(x):
      	return -x
      
      function code(x)
      	return Float64(-x)
      end
      
      function tmp = code(x)
      	tmp = -x;
      end
      
      code[x_] := (-x)
      
      \begin{array}{l}
      
      \\
      -x
      \end{array}
      
      Derivation
      1. Initial program 15.9%

        \[\log \left(x + \sqrt{x \cdot x + 1}\right) \]
      2. Add Preprocessing
      3. Taylor expanded in x around 0

        \[\leadsto \color{blue}{x \cdot \left(1 + \frac{-1}{6} \cdot {x}^{2}\right)} \]
      4. Step-by-step derivation
        1. distribute-rgt-inN/A

          \[\leadsto \color{blue}{1 \cdot x + \left(\frac{-1}{6} \cdot {x}^{2}\right) \cdot x} \]
        2. *-lft-identityN/A

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

          \[\leadsto \color{blue}{\left(\frac{-1}{6} \cdot {x}^{2}\right) \cdot x + x} \]
        4. associate-*l*N/A

          \[\leadsto \color{blue}{\frac{-1}{6} \cdot \left({x}^{2} \cdot x\right)} + x \]
        5. *-commutativeN/A

          \[\leadsto \color{blue}{\left({x}^{2} \cdot x\right) \cdot \frac{-1}{6}} + x \]
        6. lower-fma.f64N/A

          \[\leadsto \color{blue}{\mathsf{fma}\left({x}^{2} \cdot x, \frac{-1}{6}, x\right)} \]
        7. pow-plusN/A

          \[\leadsto \mathsf{fma}\left(\color{blue}{{x}^{\left(2 + 1\right)}}, \frac{-1}{6}, x\right) \]
        8. lower-pow.f64N/A

          \[\leadsto \mathsf{fma}\left(\color{blue}{{x}^{\left(2 + 1\right)}}, \frac{-1}{6}, x\right) \]
        9. metadata-eval49.1

          \[\leadsto \mathsf{fma}\left({x}^{\color{blue}{3}}, -0.16666666666666666, x\right) \]
      5. Applied rewrites49.1%

        \[\leadsto \color{blue}{\mathsf{fma}\left({x}^{3}, -0.16666666666666666, x\right)} \]
      6. Applied rewrites3.8%

        \[\leadsto \mathsf{fma}\left(0.16666666666666666 \cdot x, \color{blue}{x \cdot x}, -x\right) \]
      7. Taylor expanded in x around 0

        \[\leadsto -1 \cdot \color{blue}{x} \]
      8. Step-by-step derivation
        1. Applied rewrites2.4%

          \[\leadsto -x \]
        2. Add Preprocessing

        Developer Target 1: 29.7% accurate, 0.9× speedup?

        \[\begin{array}{l} \\ \begin{array}{l} t_0 := \sqrt{x \cdot x + 1}\\ \mathbf{if}\;x < 0:\\ \;\;\;\;\log \left(\frac{-1}{x - t\_0}\right)\\ \mathbf{else}:\\ \;\;\;\;\log \left(x + t\_0\right)\\ \end{array} \end{array} \]
        (FPCore (x)
         :precision binary64
         (let* ((t_0 (sqrt (+ (* x x) 1.0))))
           (if (< x 0.0) (log (/ -1.0 (- x t_0))) (log (+ x t_0)))))
        double code(double x) {
        	double t_0 = sqrt(((x * x) + 1.0));
        	double tmp;
        	if (x < 0.0) {
        		tmp = log((-1.0 / (x - t_0)));
        	} else {
        		tmp = log((x + t_0));
        	}
        	return tmp;
        }
        
        real(8) function code(x)
            real(8), intent (in) :: x
            real(8) :: t_0
            real(8) :: tmp
            t_0 = sqrt(((x * x) + 1.0d0))
            if (x < 0.0d0) then
                tmp = log(((-1.0d0) / (x - t_0)))
            else
                tmp = log((x + t_0))
            end if
            code = tmp
        end function
        
        public static double code(double x) {
        	double t_0 = Math.sqrt(((x * x) + 1.0));
        	double tmp;
        	if (x < 0.0) {
        		tmp = Math.log((-1.0 / (x - t_0)));
        	} else {
        		tmp = Math.log((x + t_0));
        	}
        	return tmp;
        }
        
        def code(x):
        	t_0 = math.sqrt(((x * x) + 1.0))
        	tmp = 0
        	if x < 0.0:
        		tmp = math.log((-1.0 / (x - t_0)))
        	else:
        		tmp = math.log((x + t_0))
        	return tmp
        
        function code(x)
        	t_0 = sqrt(Float64(Float64(x * x) + 1.0))
        	tmp = 0.0
        	if (x < 0.0)
        		tmp = log(Float64(-1.0 / Float64(x - t_0)));
        	else
        		tmp = log(Float64(x + t_0));
        	end
        	return tmp
        end
        
        function tmp_2 = code(x)
        	t_0 = sqrt(((x * x) + 1.0));
        	tmp = 0.0;
        	if (x < 0.0)
        		tmp = log((-1.0 / (x - t_0)));
        	else
        		tmp = log((x + t_0));
        	end
        	tmp_2 = tmp;
        end
        
        code[x_] := Block[{t$95$0 = N[Sqrt[N[(N[(x * x), $MachinePrecision] + 1.0), $MachinePrecision]], $MachinePrecision]}, If[Less[x, 0.0], N[Log[N[(-1.0 / N[(x - t$95$0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision], N[Log[N[(x + t$95$0), $MachinePrecision]], $MachinePrecision]]]
        
        \begin{array}{l}
        
        \\
        \begin{array}{l}
        t_0 := \sqrt{x \cdot x + 1}\\
        \mathbf{if}\;x < 0:\\
        \;\;\;\;\log \left(\frac{-1}{x - t\_0}\right)\\
        
        \mathbf{else}:\\
        \;\;\;\;\log \left(x + t\_0\right)\\
        
        
        \end{array}
        \end{array}
        

        Reproduce

        ?
        herbie shell --seed 2024326 
        (FPCore (x)
          :name "Hyperbolic arcsine"
          :precision binary64
        
          :alt
          (! :herbie-platform default (if (< x 0) (log (/ -1 (- x (sqrt (+ (* x x) 1))))) (log (+ x (sqrt (+ (* x x) 1))))))
        
          (log (+ x (sqrt (+ (* x x) 1.0)))))