Asymptote A

Percentage Accurate: 76.9% → 99.9%
Time: 7.2s
Alternatives: 5
Speedup: 1.2×

Specification

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

\\
\frac{1}{x + 1} - \frac{1}{x - 1}
\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: 76.9% accurate, 1.0× speedup?

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

\\
\frac{1}{x + 1} - \frac{1}{x - 1}
\end{array}

Alternative 1: 99.9% accurate, 1.2× speedup?

\[\begin{array}{l} x_m = \left|x\right| \\ \frac{\frac{-2}{1 + x\_m}}{x\_m + -1} \end{array} \]
x_m = (fabs.f64 x)
(FPCore (x_m) :precision binary64 (/ (/ -2.0 (+ 1.0 x_m)) (+ x_m -1.0)))
x_m = fabs(x);
double code(double x_m) {
	return (-2.0 / (1.0 + x_m)) / (x_m + -1.0);
}
x_m = abs(x)
real(8) function code(x_m)
    real(8), intent (in) :: x_m
    code = ((-2.0d0) / (1.0d0 + x_m)) / (x_m + (-1.0d0))
end function
x_m = Math.abs(x);
public static double code(double x_m) {
	return (-2.0 / (1.0 + x_m)) / (x_m + -1.0);
}
x_m = math.fabs(x)
def code(x_m):
	return (-2.0 / (1.0 + x_m)) / (x_m + -1.0)
x_m = abs(x)
function code(x_m)
	return Float64(Float64(-2.0 / Float64(1.0 + x_m)) / Float64(x_m + -1.0))
end
x_m = abs(x);
function tmp = code(x_m)
	tmp = (-2.0 / (1.0 + x_m)) / (x_m + -1.0);
end
x_m = N[Abs[x], $MachinePrecision]
code[x$95$m_] := N[(N[(-2.0 / N[(1.0 + x$95$m), $MachinePrecision]), $MachinePrecision] / N[(x$95$m + -1.0), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
x_m = \left|x\right|

\\
\frac{\frac{-2}{1 + x\_m}}{x\_m + -1}
\end{array}
Derivation
  1. Initial program 77.6%

    \[\frac{1}{x + 1} - \frac{1}{x - 1} \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. clear-numN/A

      \[\leadsto \frac{1}{\frac{x + 1}{1}} - \frac{\color{blue}{1}}{x - 1} \]
    2. frac-subN/A

      \[\leadsto \frac{1 \cdot \left(x - 1\right) - \frac{x + 1}{1} \cdot 1}{\color{blue}{\frac{x + 1}{1} \cdot \left(x - 1\right)}} \]
    3. div-invN/A

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

      \[\leadsto \frac{1 \cdot \left(x - 1\right) - \left(\left(x + 1\right) \cdot 1\right) \cdot 1}{\frac{x + 1}{1} \cdot \left(x - 1\right)} \]
    5. *-rgt-identityN/A

      \[\leadsto \frac{1 \cdot \left(x - 1\right) - \left(x + 1\right) \cdot 1}{\frac{x + 1}{1} \cdot \left(x - 1\right)} \]
    6. associate-/r*N/A

      \[\leadsto \frac{\frac{1 \cdot \left(x - 1\right) - \left(x + 1\right) \cdot 1}{\frac{x + 1}{1}}}{\color{blue}{x - 1}} \]
    7. /-lowering-/.f64N/A

      \[\leadsto \mathsf{/.f64}\left(\left(\frac{1 \cdot \left(x - 1\right) - \left(x + 1\right) \cdot 1}{\frac{x + 1}{1}}\right), \color{blue}{\left(x - 1\right)}\right) \]
  4. Applied egg-rr81.3%

    \[\leadsto \color{blue}{\frac{\frac{-1 + \left(x + \left(-1 - x\right)\right)}{1 + x}}{x + -1}} \]
  5. Taylor expanded in x around 0

    \[\leadsto \mathsf{/.f64}\left(\mathsf{/.f64}\left(\color{blue}{-2}, \mathsf{+.f64}\left(1, x\right)\right), \mathsf{+.f64}\left(x, -1\right)\right) \]
  6. Step-by-step derivation
    1. Simplified99.9%

      \[\leadsto \frac{\frac{\color{blue}{-2}}{1 + x}}{x + -1} \]
    2. Add Preprocessing

    Alternative 2: 99.0% accurate, 0.9× speedup?

    \[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} \mathbf{if}\;x\_m \leq 1:\\ \;\;\;\;2 + 2 \cdot \left(x\_m \cdot x\_m\right)\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{-2}{x\_m}}{x\_m}\\ \end{array} \end{array} \]
    x_m = (fabs.f64 x)
    (FPCore (x_m)
     :precision binary64
     (if (<= x_m 1.0) (+ 2.0 (* 2.0 (* x_m x_m))) (/ (/ -2.0 x_m) x_m)))
    x_m = fabs(x);
    double code(double x_m) {
    	double tmp;
    	if (x_m <= 1.0) {
    		tmp = 2.0 + (2.0 * (x_m * x_m));
    	} else {
    		tmp = (-2.0 / x_m) / x_m;
    	}
    	return tmp;
    }
    
    x_m = abs(x)
    real(8) function code(x_m)
        real(8), intent (in) :: x_m
        real(8) :: tmp
        if (x_m <= 1.0d0) then
            tmp = 2.0d0 + (2.0d0 * (x_m * x_m))
        else
            tmp = ((-2.0d0) / x_m) / x_m
        end if
        code = tmp
    end function
    
    x_m = Math.abs(x);
    public static double code(double x_m) {
    	double tmp;
    	if (x_m <= 1.0) {
    		tmp = 2.0 + (2.0 * (x_m * x_m));
    	} else {
    		tmp = (-2.0 / x_m) / x_m;
    	}
    	return tmp;
    }
    
    x_m = math.fabs(x)
    def code(x_m):
    	tmp = 0
    	if x_m <= 1.0:
    		tmp = 2.0 + (2.0 * (x_m * x_m))
    	else:
    		tmp = (-2.0 / x_m) / x_m
    	return tmp
    
    x_m = abs(x)
    function code(x_m)
    	tmp = 0.0
    	if (x_m <= 1.0)
    		tmp = Float64(2.0 + Float64(2.0 * Float64(x_m * x_m)));
    	else
    		tmp = Float64(Float64(-2.0 / x_m) / x_m);
    	end
    	return tmp
    end
    
    x_m = abs(x);
    function tmp_2 = code(x_m)
    	tmp = 0.0;
    	if (x_m <= 1.0)
    		tmp = 2.0 + (2.0 * (x_m * x_m));
    	else
    		tmp = (-2.0 / x_m) / x_m;
    	end
    	tmp_2 = tmp;
    end
    
    x_m = N[Abs[x], $MachinePrecision]
    code[x$95$m_] := If[LessEqual[x$95$m, 1.0], N[(2.0 + N[(2.0 * N[(x$95$m * x$95$m), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(N[(-2.0 / x$95$m), $MachinePrecision] / x$95$m), $MachinePrecision]]
    
    \begin{array}{l}
    x_m = \left|x\right|
    
    \\
    \begin{array}{l}
    \mathbf{if}\;x\_m \leq 1:\\
    \;\;\;\;2 + 2 \cdot \left(x\_m \cdot x\_m\right)\\
    
    \mathbf{else}:\\
    \;\;\;\;\frac{\frac{-2}{x\_m}}{x\_m}\\
    
    
    \end{array}
    \end{array}
    
    Derivation
    1. Split input into 2 regimes
    2. if x < 1

      1. Initial program 85.6%

        \[\frac{1}{x + 1} - \frac{1}{x - 1} \]
      2. Add Preprocessing
      3. Taylor expanded in x around 0

        \[\leadsto \color{blue}{2 + 2 \cdot {x}^{2}} \]
      4. Step-by-step derivation
        1. +-lowering-+.f64N/A

          \[\leadsto \mathsf{+.f64}\left(2, \color{blue}{\left(2 \cdot {x}^{2}\right)}\right) \]
        2. *-lowering-*.f64N/A

          \[\leadsto \mathsf{+.f64}\left(2, \mathsf{*.f64}\left(2, \color{blue}{\left({x}^{2}\right)}\right)\right) \]
        3. unpow2N/A

          \[\leadsto \mathsf{+.f64}\left(2, \mathsf{*.f64}\left(2, \left(x \cdot \color{blue}{x}\right)\right)\right) \]
        4. *-lowering-*.f6467.4%

          \[\leadsto \mathsf{+.f64}\left(2, \mathsf{*.f64}\left(2, \mathsf{*.f64}\left(x, \color{blue}{x}\right)\right)\right) \]
      5. Simplified67.4%

        \[\leadsto \color{blue}{2 + 2 \cdot \left(x \cdot x\right)} \]

      if 1 < x

      1. Initial program 56.6%

        \[\frac{1}{x + 1} - \frac{1}{x - 1} \]
      2. Add Preprocessing
      3. Taylor expanded in x around inf

        \[\leadsto \color{blue}{\frac{-2}{{x}^{2}}} \]
      4. Step-by-step derivation
        1. /-lowering-/.f64N/A

          \[\leadsto \mathsf{/.f64}\left(-2, \color{blue}{\left({x}^{2}\right)}\right) \]
        2. unpow2N/A

          \[\leadsto \mathsf{/.f64}\left(-2, \left(x \cdot \color{blue}{x}\right)\right) \]
        3. *-lowering-*.f6498.2%

          \[\leadsto \mathsf{/.f64}\left(-2, \mathsf{*.f64}\left(x, \color{blue}{x}\right)\right) \]
      5. Simplified98.2%

        \[\leadsto \color{blue}{\frac{-2}{x \cdot x}} \]
      6. Step-by-step derivation
        1. associate-/r*N/A

          \[\leadsto \frac{\frac{-2}{x}}{\color{blue}{x}} \]
        2. /-lowering-/.f64N/A

          \[\leadsto \mathsf{/.f64}\left(\left(\frac{-2}{x}\right), \color{blue}{x}\right) \]
        3. /-lowering-/.f6499.9%

          \[\leadsto \mathsf{/.f64}\left(\mathsf{/.f64}\left(-2, x\right), x\right) \]
      7. Applied egg-rr99.9%

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

    Alternative 3: 98.8% accurate, 1.1× speedup?

    \[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} \mathbf{if}\;x\_m \leq 1:\\ \;\;\;\;2\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{-2}{x\_m}}{x\_m}\\ \end{array} \end{array} \]
    x_m = (fabs.f64 x)
    (FPCore (x_m) :precision binary64 (if (<= x_m 1.0) 2.0 (/ (/ -2.0 x_m) x_m)))
    x_m = fabs(x);
    double code(double x_m) {
    	double tmp;
    	if (x_m <= 1.0) {
    		tmp = 2.0;
    	} else {
    		tmp = (-2.0 / x_m) / x_m;
    	}
    	return tmp;
    }
    
    x_m = abs(x)
    real(8) function code(x_m)
        real(8), intent (in) :: x_m
        real(8) :: tmp
        if (x_m <= 1.0d0) then
            tmp = 2.0d0
        else
            tmp = ((-2.0d0) / x_m) / x_m
        end if
        code = tmp
    end function
    
    x_m = Math.abs(x);
    public static double code(double x_m) {
    	double tmp;
    	if (x_m <= 1.0) {
    		tmp = 2.0;
    	} else {
    		tmp = (-2.0 / x_m) / x_m;
    	}
    	return tmp;
    }
    
    x_m = math.fabs(x)
    def code(x_m):
    	tmp = 0
    	if x_m <= 1.0:
    		tmp = 2.0
    	else:
    		tmp = (-2.0 / x_m) / x_m
    	return tmp
    
    x_m = abs(x)
    function code(x_m)
    	tmp = 0.0
    	if (x_m <= 1.0)
    		tmp = 2.0;
    	else
    		tmp = Float64(Float64(-2.0 / x_m) / x_m);
    	end
    	return tmp
    end
    
    x_m = abs(x);
    function tmp_2 = code(x_m)
    	tmp = 0.0;
    	if (x_m <= 1.0)
    		tmp = 2.0;
    	else
    		tmp = (-2.0 / x_m) / x_m;
    	end
    	tmp_2 = tmp;
    end
    
    x_m = N[Abs[x], $MachinePrecision]
    code[x$95$m_] := If[LessEqual[x$95$m, 1.0], 2.0, N[(N[(-2.0 / x$95$m), $MachinePrecision] / x$95$m), $MachinePrecision]]
    
    \begin{array}{l}
    x_m = \left|x\right|
    
    \\
    \begin{array}{l}
    \mathbf{if}\;x\_m \leq 1:\\
    \;\;\;\;2\\
    
    \mathbf{else}:\\
    \;\;\;\;\frac{\frac{-2}{x\_m}}{x\_m}\\
    
    
    \end{array}
    \end{array}
    
    Derivation
    1. Split input into 2 regimes
    2. if x < 1

      1. Initial program 85.6%

        \[\frac{1}{x + 1} - \frac{1}{x - 1} \]
      2. Add Preprocessing
      3. Taylor expanded in x around 0

        \[\leadsto \color{blue}{2} \]
      4. Step-by-step derivation
        1. Simplified67.2%

          \[\leadsto \color{blue}{2} \]

        if 1 < x

        1. Initial program 56.6%

          \[\frac{1}{x + 1} - \frac{1}{x - 1} \]
        2. Add Preprocessing
        3. Taylor expanded in x around inf

          \[\leadsto \color{blue}{\frac{-2}{{x}^{2}}} \]
        4. Step-by-step derivation
          1. /-lowering-/.f64N/A

            \[\leadsto \mathsf{/.f64}\left(-2, \color{blue}{\left({x}^{2}\right)}\right) \]
          2. unpow2N/A

            \[\leadsto \mathsf{/.f64}\left(-2, \left(x \cdot \color{blue}{x}\right)\right) \]
          3. *-lowering-*.f6498.2%

            \[\leadsto \mathsf{/.f64}\left(-2, \mathsf{*.f64}\left(x, \color{blue}{x}\right)\right) \]
        5. Simplified98.2%

          \[\leadsto \color{blue}{\frac{-2}{x \cdot x}} \]
        6. Step-by-step derivation
          1. associate-/r*N/A

            \[\leadsto \frac{\frac{-2}{x}}{\color{blue}{x}} \]
          2. /-lowering-/.f64N/A

            \[\leadsto \mathsf{/.f64}\left(\left(\frac{-2}{x}\right), \color{blue}{x}\right) \]
          3. /-lowering-/.f6499.9%

            \[\leadsto \mathsf{/.f64}\left(\mathsf{/.f64}\left(-2, x\right), x\right) \]
        7. Applied egg-rr99.9%

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

      Alternative 4: 98.2% accurate, 1.1× speedup?

      \[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} \mathbf{if}\;x\_m \leq 1:\\ \;\;\;\;2\\ \mathbf{else}:\\ \;\;\;\;\frac{-2}{x\_m \cdot x\_m}\\ \end{array} \end{array} \]
      x_m = (fabs.f64 x)
      (FPCore (x_m) :precision binary64 (if (<= x_m 1.0) 2.0 (/ -2.0 (* x_m x_m))))
      x_m = fabs(x);
      double code(double x_m) {
      	double tmp;
      	if (x_m <= 1.0) {
      		tmp = 2.0;
      	} else {
      		tmp = -2.0 / (x_m * x_m);
      	}
      	return tmp;
      }
      
      x_m = abs(x)
      real(8) function code(x_m)
          real(8), intent (in) :: x_m
          real(8) :: tmp
          if (x_m <= 1.0d0) then
              tmp = 2.0d0
          else
              tmp = (-2.0d0) / (x_m * x_m)
          end if
          code = tmp
      end function
      
      x_m = Math.abs(x);
      public static double code(double x_m) {
      	double tmp;
      	if (x_m <= 1.0) {
      		tmp = 2.0;
      	} else {
      		tmp = -2.0 / (x_m * x_m);
      	}
      	return tmp;
      }
      
      x_m = math.fabs(x)
      def code(x_m):
      	tmp = 0
      	if x_m <= 1.0:
      		tmp = 2.0
      	else:
      		tmp = -2.0 / (x_m * x_m)
      	return tmp
      
      x_m = abs(x)
      function code(x_m)
      	tmp = 0.0
      	if (x_m <= 1.0)
      		tmp = 2.0;
      	else
      		tmp = Float64(-2.0 / Float64(x_m * x_m));
      	end
      	return tmp
      end
      
      x_m = abs(x);
      function tmp_2 = code(x_m)
      	tmp = 0.0;
      	if (x_m <= 1.0)
      		tmp = 2.0;
      	else
      		tmp = -2.0 / (x_m * x_m);
      	end
      	tmp_2 = tmp;
      end
      
      x_m = N[Abs[x], $MachinePrecision]
      code[x$95$m_] := If[LessEqual[x$95$m, 1.0], 2.0, N[(-2.0 / N[(x$95$m * x$95$m), $MachinePrecision]), $MachinePrecision]]
      
      \begin{array}{l}
      x_m = \left|x\right|
      
      \\
      \begin{array}{l}
      \mathbf{if}\;x\_m \leq 1:\\
      \;\;\;\;2\\
      
      \mathbf{else}:\\
      \;\;\;\;\frac{-2}{x\_m \cdot x\_m}\\
      
      
      \end{array}
      \end{array}
      
      Derivation
      1. Split input into 2 regimes
      2. if x < 1

        1. Initial program 85.6%

          \[\frac{1}{x + 1} - \frac{1}{x - 1} \]
        2. Add Preprocessing
        3. Taylor expanded in x around 0

          \[\leadsto \color{blue}{2} \]
        4. Step-by-step derivation
          1. Simplified67.2%

            \[\leadsto \color{blue}{2} \]

          if 1 < x

          1. Initial program 56.6%

            \[\frac{1}{x + 1} - \frac{1}{x - 1} \]
          2. Add Preprocessing
          3. Taylor expanded in x around inf

            \[\leadsto \color{blue}{\frac{-2}{{x}^{2}}} \]
          4. Step-by-step derivation
            1. /-lowering-/.f64N/A

              \[\leadsto \mathsf{/.f64}\left(-2, \color{blue}{\left({x}^{2}\right)}\right) \]
            2. unpow2N/A

              \[\leadsto \mathsf{/.f64}\left(-2, \left(x \cdot \color{blue}{x}\right)\right) \]
            3. *-lowering-*.f6498.2%

              \[\leadsto \mathsf{/.f64}\left(-2, \mathsf{*.f64}\left(x, \color{blue}{x}\right)\right) \]
          5. Simplified98.2%

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

        Alternative 5: 50.6% accurate, 11.0× speedup?

        \[\begin{array}{l} x_m = \left|x\right| \\ 2 \end{array} \]
        x_m = (fabs.f64 x)
        (FPCore (x_m) :precision binary64 2.0)
        x_m = fabs(x);
        double code(double x_m) {
        	return 2.0;
        }
        
        x_m = abs(x)
        real(8) function code(x_m)
            real(8), intent (in) :: x_m
            code = 2.0d0
        end function
        
        x_m = Math.abs(x);
        public static double code(double x_m) {
        	return 2.0;
        }
        
        x_m = math.fabs(x)
        def code(x_m):
        	return 2.0
        
        x_m = abs(x)
        function code(x_m)
        	return 2.0
        end
        
        x_m = abs(x);
        function tmp = code(x_m)
        	tmp = 2.0;
        end
        
        x_m = N[Abs[x], $MachinePrecision]
        code[x$95$m_] := 2.0
        
        \begin{array}{l}
        x_m = \left|x\right|
        
        \\
        2
        \end{array}
        
        Derivation
        1. Initial program 77.6%

          \[\frac{1}{x + 1} - \frac{1}{x - 1} \]
        2. Add Preprocessing
        3. Taylor expanded in x around 0

          \[\leadsto \color{blue}{2} \]
        4. Step-by-step derivation
          1. Simplified49.6%

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

          Reproduce

          ?
          herbie shell --seed 2024150 
          (FPCore (x)
            :name "Asymptote A"
            :precision binary64
            (- (/ 1.0 (+ x 1.0)) (/ 1.0 (- x 1.0))))