Asymptote B

Percentage Accurate: 100.0% → 100.0%
Time: 4.1s
Alternatives: 5
Speedup: 1.0×

Specification

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

\\
\frac{1}{x - 1} + \frac{x}{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: 100.0% accurate, 1.0× speedup?

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

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

Alternative 1: 100.0% accurate, 1.0× speedup?

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

\\
\frac{x}{1 + x} + \frac{1}{x + -1}
\end{array}
Derivation
  1. Initial program 100.0%

    \[\frac{1}{x - 1} + \frac{x}{x + 1} \]
  2. Final simplification100.0%

    \[\leadsto \frac{x}{1 + x} + \frac{1}{x + -1} \]

Alternative 2: 99.0% accurate, 0.8× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq -0.55 \lor \neg \left(x \leq 1.82\right):\\ \;\;\;\;\frac{1}{x} - \frac{x}{-1 - x}\\ \mathbf{else}:\\ \;\;\;\;x + \frac{1}{x + -1}\\ \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (if (or (<= x -0.55) (not (<= x 1.82)))
   (- (/ 1.0 x) (/ x (- -1.0 x)))
   (+ x (/ 1.0 (+ x -1.0)))))
double code(double x) {
	double tmp;
	if ((x <= -0.55) || !(x <= 1.82)) {
		tmp = (1.0 / x) - (x / (-1.0 - x));
	} else {
		tmp = x + (1.0 / (x + -1.0));
	}
	return tmp;
}
real(8) function code(x)
    real(8), intent (in) :: x
    real(8) :: tmp
    if ((x <= (-0.55d0)) .or. (.not. (x <= 1.82d0))) then
        tmp = (1.0d0 / x) - (x / ((-1.0d0) - x))
    else
        tmp = x + (1.0d0 / (x + (-1.0d0)))
    end if
    code = tmp
end function
public static double code(double x) {
	double tmp;
	if ((x <= -0.55) || !(x <= 1.82)) {
		tmp = (1.0 / x) - (x / (-1.0 - x));
	} else {
		tmp = x + (1.0 / (x + -1.0));
	}
	return tmp;
}
def code(x):
	tmp = 0
	if (x <= -0.55) or not (x <= 1.82):
		tmp = (1.0 / x) - (x / (-1.0 - x))
	else:
		tmp = x + (1.0 / (x + -1.0))
	return tmp
function code(x)
	tmp = 0.0
	if ((x <= -0.55) || !(x <= 1.82))
		tmp = Float64(Float64(1.0 / x) - Float64(x / Float64(-1.0 - x)));
	else
		tmp = Float64(x + Float64(1.0 / Float64(x + -1.0)));
	end
	return tmp
end
function tmp_2 = code(x)
	tmp = 0.0;
	if ((x <= -0.55) || ~((x <= 1.82)))
		tmp = (1.0 / x) - (x / (-1.0 - x));
	else
		tmp = x + (1.0 / (x + -1.0));
	end
	tmp_2 = tmp;
end
code[x_] := If[Or[LessEqual[x, -0.55], N[Not[LessEqual[x, 1.82]], $MachinePrecision]], N[(N[(1.0 / x), $MachinePrecision] - N[(x / N[(-1.0 - x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(x + N[(1.0 / N[(x + -1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq -0.55 \lor \neg \left(x \leq 1.82\right):\\
\;\;\;\;\frac{1}{x} - \frac{x}{-1 - x}\\

\mathbf{else}:\\
\;\;\;\;x + \frac{1}{x + -1}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < -0.55000000000000004 or 1.82000000000000006 < x

    1. Initial program 100.0%

      \[\frac{1}{x - 1} + \frac{x}{x + 1} \]
    2. Step-by-step derivation
      1. remove-double-neg100.0%

        \[\leadsto \frac{1}{x - 1} + \frac{\color{blue}{-\left(-x\right)}}{x + 1} \]
      2. distribute-frac-neg100.0%

        \[\leadsto \frac{1}{x - 1} + \color{blue}{\left(-\frac{-x}{x + 1}\right)} \]
      3. unsub-neg100.0%

        \[\leadsto \color{blue}{\frac{1}{x - 1} - \frac{-x}{x + 1}} \]
      4. sub-neg100.0%

        \[\leadsto \frac{1}{\color{blue}{x + \left(-1\right)}} - \frac{-x}{x + 1} \]
      5. metadata-eval100.0%

        \[\leadsto \frac{1}{x + \color{blue}{-1}} - \frac{-x}{x + 1} \]
      6. neg-mul-1100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{-1 \cdot x}}{x + 1} \]
      7. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{\left(-1\right)} \cdot x}{x + 1} \]
      8. *-commutative100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{x \cdot \left(-1\right)}}{x + 1} \]
      9. associate-/l*100.0%

        \[\leadsto \frac{1}{x + -1} - \color{blue}{\frac{x}{\frac{x + 1}{-1}}} \]
      10. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\color{blue}{-1}}} \]
      11. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\color{blue}{\frac{1}{-1}}}} \]
      12. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\frac{1}{\color{blue}{-1}}}} \]
      13. associate-/l*100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\frac{\left(x + 1\right) \cdot \left(-1\right)}{1}}} \]
      14. associate-*l/100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\frac{x + 1}{1} \cdot \left(-1\right)}} \]
      15. /-rgt-identity100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(x + 1\right)} \cdot \left(-1\right)} \]
      16. distribute-rgt1-in100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(-1\right) + x \cdot \left(-1\right)}} \]
      17. *-commutative100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{\left(-1\right) \cdot x}} \]
      18. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{-1} \cdot x} \]
      19. neg-mul-1100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{\left(-x\right)}} \]
      20. unsub-neg100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(-1\right) - x}} \]
      21. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{-1} - x} \]
    3. Simplified100.0%

      \[\leadsto \color{blue}{\frac{1}{x + -1} - \frac{x}{-1 - x}} \]
    4. Taylor expanded in x around inf 98.8%

      \[\leadsto \color{blue}{\frac{1}{x}} - \frac{x}{-1 - x} \]

    if -0.55000000000000004 < x < 1.82000000000000006

    1. Initial program 100.0%

      \[\frac{1}{x - 1} + \frac{x}{x + 1} \]
    2. Step-by-step derivation
      1. remove-double-neg100.0%

        \[\leadsto \frac{1}{x - 1} + \frac{\color{blue}{-\left(-x\right)}}{x + 1} \]
      2. distribute-frac-neg100.0%

        \[\leadsto \frac{1}{x - 1} + \color{blue}{\left(-\frac{-x}{x + 1}\right)} \]
      3. unsub-neg100.0%

        \[\leadsto \color{blue}{\frac{1}{x - 1} - \frac{-x}{x + 1}} \]
      4. sub-neg100.0%

        \[\leadsto \frac{1}{\color{blue}{x + \left(-1\right)}} - \frac{-x}{x + 1} \]
      5. metadata-eval100.0%

        \[\leadsto \frac{1}{x + \color{blue}{-1}} - \frac{-x}{x + 1} \]
      6. neg-mul-1100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{-1 \cdot x}}{x + 1} \]
      7. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{\left(-1\right)} \cdot x}{x + 1} \]
      8. *-commutative100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{x \cdot \left(-1\right)}}{x + 1} \]
      9. associate-/l*100.0%

        \[\leadsto \frac{1}{x + -1} - \color{blue}{\frac{x}{\frac{x + 1}{-1}}} \]
      10. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\color{blue}{-1}}} \]
      11. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\color{blue}{\frac{1}{-1}}}} \]
      12. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\frac{1}{\color{blue}{-1}}}} \]
      13. associate-/l*100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\frac{\left(x + 1\right) \cdot \left(-1\right)}{1}}} \]
      14. associate-*l/100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\frac{x + 1}{1} \cdot \left(-1\right)}} \]
      15. /-rgt-identity100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(x + 1\right)} \cdot \left(-1\right)} \]
      16. distribute-rgt1-in100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(-1\right) + x \cdot \left(-1\right)}} \]
      17. *-commutative100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{\left(-1\right) \cdot x}} \]
      18. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{-1} \cdot x} \]
      19. neg-mul-1100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{\left(-x\right)}} \]
      20. unsub-neg100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(-1\right) - x}} \]
      21. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{-1} - x} \]
    3. Simplified100.0%

      \[\leadsto \color{blue}{\frac{1}{x + -1} - \frac{x}{-1 - x}} \]
    4. Taylor expanded in x around 0 99.3%

      \[\leadsto \frac{1}{x + -1} - \color{blue}{-1 \cdot x} \]
    5. Step-by-step derivation
      1. neg-mul-199.3%

        \[\leadsto \frac{1}{x + -1} - \color{blue}{\left(-x\right)} \]
    6. Simplified99.3%

      \[\leadsto \frac{1}{x + -1} - \color{blue}{\left(-x\right)} \]
    7. Step-by-step derivation
      1. sub-neg99.3%

        \[\leadsto \color{blue}{\frac{1}{x + -1} + \left(-\left(-x\right)\right)} \]
      2. +-commutative99.3%

        \[\leadsto \frac{1}{\color{blue}{-1 + x}} + \left(-\left(-x\right)\right) \]
      3. remove-double-neg99.3%

        \[\leadsto \frac{1}{-1 + x} + \color{blue}{x} \]
    8. Applied egg-rr99.3%

      \[\leadsto \color{blue}{\frac{1}{-1 + x} + x} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification99.1%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -0.55 \lor \neg \left(x \leq 1.82\right):\\ \;\;\;\;\frac{1}{x} - \frac{x}{-1 - x}\\ \mathbf{else}:\\ \;\;\;\;x + \frac{1}{x + -1}\\ \end{array} \]

Alternative 3: 99.0% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq -1:\\ \;\;\;\;1\\ \mathbf{elif}\;x \leq 1.9:\\ \;\;\;\;x + \frac{1}{x + -1}\\ \mathbf{else}:\\ \;\;\;\;1\\ \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (if (<= x -1.0) 1.0 (if (<= x 1.9) (+ x (/ 1.0 (+ x -1.0))) 1.0)))
double code(double x) {
	double tmp;
	if (x <= -1.0) {
		tmp = 1.0;
	} else if (x <= 1.9) {
		tmp = x + (1.0 / (x + -1.0));
	} else {
		tmp = 1.0;
	}
	return tmp;
}
real(8) function code(x)
    real(8), intent (in) :: x
    real(8) :: tmp
    if (x <= (-1.0d0)) then
        tmp = 1.0d0
    else if (x <= 1.9d0) then
        tmp = x + (1.0d0 / (x + (-1.0d0)))
    else
        tmp = 1.0d0
    end if
    code = tmp
end function
public static double code(double x) {
	double tmp;
	if (x <= -1.0) {
		tmp = 1.0;
	} else if (x <= 1.9) {
		tmp = x + (1.0 / (x + -1.0));
	} else {
		tmp = 1.0;
	}
	return tmp;
}
def code(x):
	tmp = 0
	if x <= -1.0:
		tmp = 1.0
	elif x <= 1.9:
		tmp = x + (1.0 / (x + -1.0))
	else:
		tmp = 1.0
	return tmp
function code(x)
	tmp = 0.0
	if (x <= -1.0)
		tmp = 1.0;
	elseif (x <= 1.9)
		tmp = Float64(x + Float64(1.0 / Float64(x + -1.0)));
	else
		tmp = 1.0;
	end
	return tmp
end
function tmp_2 = code(x)
	tmp = 0.0;
	if (x <= -1.0)
		tmp = 1.0;
	elseif (x <= 1.9)
		tmp = x + (1.0 / (x + -1.0));
	else
		tmp = 1.0;
	end
	tmp_2 = tmp;
end
code[x_] := If[LessEqual[x, -1.0], 1.0, If[LessEqual[x, 1.9], N[(x + N[(1.0 / N[(x + -1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], 1.0]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq -1:\\
\;\;\;\;1\\

\mathbf{elif}\;x \leq 1.9:\\
\;\;\;\;x + \frac{1}{x + -1}\\

\mathbf{else}:\\
\;\;\;\;1\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < -1 or 1.8999999999999999 < x

    1. Initial program 100.0%

      \[\frac{1}{x - 1} + \frac{x}{x + 1} \]
    2. Step-by-step derivation
      1. remove-double-neg100.0%

        \[\leadsto \frac{1}{x - 1} + \frac{\color{blue}{-\left(-x\right)}}{x + 1} \]
      2. distribute-frac-neg100.0%

        \[\leadsto \frac{1}{x - 1} + \color{blue}{\left(-\frac{-x}{x + 1}\right)} \]
      3. unsub-neg100.0%

        \[\leadsto \color{blue}{\frac{1}{x - 1} - \frac{-x}{x + 1}} \]
      4. sub-neg100.0%

        \[\leadsto \frac{1}{\color{blue}{x + \left(-1\right)}} - \frac{-x}{x + 1} \]
      5. metadata-eval100.0%

        \[\leadsto \frac{1}{x + \color{blue}{-1}} - \frac{-x}{x + 1} \]
      6. neg-mul-1100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{-1 \cdot x}}{x + 1} \]
      7. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{\left(-1\right)} \cdot x}{x + 1} \]
      8. *-commutative100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{x \cdot \left(-1\right)}}{x + 1} \]
      9. associate-/l*100.0%

        \[\leadsto \frac{1}{x + -1} - \color{blue}{\frac{x}{\frac{x + 1}{-1}}} \]
      10. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\color{blue}{-1}}} \]
      11. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\color{blue}{\frac{1}{-1}}}} \]
      12. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\frac{1}{\color{blue}{-1}}}} \]
      13. associate-/l*100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\frac{\left(x + 1\right) \cdot \left(-1\right)}{1}}} \]
      14. associate-*l/100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\frac{x + 1}{1} \cdot \left(-1\right)}} \]
      15. /-rgt-identity100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(x + 1\right)} \cdot \left(-1\right)} \]
      16. distribute-rgt1-in100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(-1\right) + x \cdot \left(-1\right)}} \]
      17. *-commutative100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{\left(-1\right) \cdot x}} \]
      18. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{-1} \cdot x} \]
      19. neg-mul-1100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{\left(-x\right)}} \]
      20. unsub-neg100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(-1\right) - x}} \]
      21. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{-1} - x} \]
    3. Simplified100.0%

      \[\leadsto \color{blue}{\frac{1}{x + -1} - \frac{x}{-1 - x}} \]
    4. Taylor expanded in x around inf 98.8%

      \[\leadsto \color{blue}{1} \]

    if -1 < x < 1.8999999999999999

    1. Initial program 100.0%

      \[\frac{1}{x - 1} + \frac{x}{x + 1} \]
    2. Step-by-step derivation
      1. remove-double-neg100.0%

        \[\leadsto \frac{1}{x - 1} + \frac{\color{blue}{-\left(-x\right)}}{x + 1} \]
      2. distribute-frac-neg100.0%

        \[\leadsto \frac{1}{x - 1} + \color{blue}{\left(-\frac{-x}{x + 1}\right)} \]
      3. unsub-neg100.0%

        \[\leadsto \color{blue}{\frac{1}{x - 1} - \frac{-x}{x + 1}} \]
      4. sub-neg100.0%

        \[\leadsto \frac{1}{\color{blue}{x + \left(-1\right)}} - \frac{-x}{x + 1} \]
      5. metadata-eval100.0%

        \[\leadsto \frac{1}{x + \color{blue}{-1}} - \frac{-x}{x + 1} \]
      6. neg-mul-1100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{-1 \cdot x}}{x + 1} \]
      7. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{\left(-1\right)} \cdot x}{x + 1} \]
      8. *-commutative100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{x \cdot \left(-1\right)}}{x + 1} \]
      9. associate-/l*100.0%

        \[\leadsto \frac{1}{x + -1} - \color{blue}{\frac{x}{\frac{x + 1}{-1}}} \]
      10. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\color{blue}{-1}}} \]
      11. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\color{blue}{\frac{1}{-1}}}} \]
      12. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\frac{1}{\color{blue}{-1}}}} \]
      13. associate-/l*100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\frac{\left(x + 1\right) \cdot \left(-1\right)}{1}}} \]
      14. associate-*l/100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\frac{x + 1}{1} \cdot \left(-1\right)}} \]
      15. /-rgt-identity100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(x + 1\right)} \cdot \left(-1\right)} \]
      16. distribute-rgt1-in100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(-1\right) + x \cdot \left(-1\right)}} \]
      17. *-commutative100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{\left(-1\right) \cdot x}} \]
      18. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{-1} \cdot x} \]
      19. neg-mul-1100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{\left(-x\right)}} \]
      20. unsub-neg100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(-1\right) - x}} \]
      21. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{-1} - x} \]
    3. Simplified100.0%

      \[\leadsto \color{blue}{\frac{1}{x + -1} - \frac{x}{-1 - x}} \]
    4. Taylor expanded in x around 0 99.3%

      \[\leadsto \frac{1}{x + -1} - \color{blue}{-1 \cdot x} \]
    5. Step-by-step derivation
      1. neg-mul-199.3%

        \[\leadsto \frac{1}{x + -1} - \color{blue}{\left(-x\right)} \]
    6. Simplified99.3%

      \[\leadsto \frac{1}{x + -1} - \color{blue}{\left(-x\right)} \]
    7. Step-by-step derivation
      1. sub-neg99.3%

        \[\leadsto \color{blue}{\frac{1}{x + -1} + \left(-\left(-x\right)\right)} \]
      2. +-commutative99.3%

        \[\leadsto \frac{1}{\color{blue}{-1 + x}} + \left(-\left(-x\right)\right) \]
      3. remove-double-neg99.3%

        \[\leadsto \frac{1}{-1 + x} + \color{blue}{x} \]
    8. Applied egg-rr99.3%

      \[\leadsto \color{blue}{\frac{1}{-1 + x} + x} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification99.0%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -1:\\ \;\;\;\;1\\ \mathbf{elif}\;x \leq 1.9:\\ \;\;\;\;x + \frac{1}{x + -1}\\ \mathbf{else}:\\ \;\;\;\;1\\ \end{array} \]

Alternative 4: 98.9% accurate, 2.1× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq -1:\\ \;\;\;\;1\\ \mathbf{elif}\;x \leq 1:\\ \;\;\;\;-1\\ \mathbf{else}:\\ \;\;\;\;1\\ \end{array} \end{array} \]
(FPCore (x) :precision binary64 (if (<= x -1.0) 1.0 (if (<= x 1.0) -1.0 1.0)))
double code(double x) {
	double tmp;
	if (x <= -1.0) {
		tmp = 1.0;
	} else if (x <= 1.0) {
		tmp = -1.0;
	} else {
		tmp = 1.0;
	}
	return tmp;
}
real(8) function code(x)
    real(8), intent (in) :: x
    real(8) :: tmp
    if (x <= (-1.0d0)) then
        tmp = 1.0d0
    else if (x <= 1.0d0) then
        tmp = -1.0d0
    else
        tmp = 1.0d0
    end if
    code = tmp
end function
public static double code(double x) {
	double tmp;
	if (x <= -1.0) {
		tmp = 1.0;
	} else if (x <= 1.0) {
		tmp = -1.0;
	} else {
		tmp = 1.0;
	}
	return tmp;
}
def code(x):
	tmp = 0
	if x <= -1.0:
		tmp = 1.0
	elif x <= 1.0:
		tmp = -1.0
	else:
		tmp = 1.0
	return tmp
function code(x)
	tmp = 0.0
	if (x <= -1.0)
		tmp = 1.0;
	elseif (x <= 1.0)
		tmp = -1.0;
	else
		tmp = 1.0;
	end
	return tmp
end
function tmp_2 = code(x)
	tmp = 0.0;
	if (x <= -1.0)
		tmp = 1.0;
	elseif (x <= 1.0)
		tmp = -1.0;
	else
		tmp = 1.0;
	end
	tmp_2 = tmp;
end
code[x_] := If[LessEqual[x, -1.0], 1.0, If[LessEqual[x, 1.0], -1.0, 1.0]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq -1:\\
\;\;\;\;1\\

\mathbf{elif}\;x \leq 1:\\
\;\;\;\;-1\\

\mathbf{else}:\\
\;\;\;\;1\\


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

    1. Initial program 100.0%

      \[\frac{1}{x - 1} + \frac{x}{x + 1} \]
    2. Step-by-step derivation
      1. remove-double-neg100.0%

        \[\leadsto \frac{1}{x - 1} + \frac{\color{blue}{-\left(-x\right)}}{x + 1} \]
      2. distribute-frac-neg100.0%

        \[\leadsto \frac{1}{x - 1} + \color{blue}{\left(-\frac{-x}{x + 1}\right)} \]
      3. unsub-neg100.0%

        \[\leadsto \color{blue}{\frac{1}{x - 1} - \frac{-x}{x + 1}} \]
      4. sub-neg100.0%

        \[\leadsto \frac{1}{\color{blue}{x + \left(-1\right)}} - \frac{-x}{x + 1} \]
      5. metadata-eval100.0%

        \[\leadsto \frac{1}{x + \color{blue}{-1}} - \frac{-x}{x + 1} \]
      6. neg-mul-1100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{-1 \cdot x}}{x + 1} \]
      7. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{\left(-1\right)} \cdot x}{x + 1} \]
      8. *-commutative100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{x \cdot \left(-1\right)}}{x + 1} \]
      9. associate-/l*100.0%

        \[\leadsto \frac{1}{x + -1} - \color{blue}{\frac{x}{\frac{x + 1}{-1}}} \]
      10. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\color{blue}{-1}}} \]
      11. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\color{blue}{\frac{1}{-1}}}} \]
      12. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\frac{1}{\color{blue}{-1}}}} \]
      13. associate-/l*100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\frac{\left(x + 1\right) \cdot \left(-1\right)}{1}}} \]
      14. associate-*l/100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\frac{x + 1}{1} \cdot \left(-1\right)}} \]
      15. /-rgt-identity100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(x + 1\right)} \cdot \left(-1\right)} \]
      16. distribute-rgt1-in100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(-1\right) + x \cdot \left(-1\right)}} \]
      17. *-commutative100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{\left(-1\right) \cdot x}} \]
      18. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{-1} \cdot x} \]
      19. neg-mul-1100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{\left(-x\right)}} \]
      20. unsub-neg100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(-1\right) - x}} \]
      21. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{-1} - x} \]
    3. Simplified100.0%

      \[\leadsto \color{blue}{\frac{1}{x + -1} - \frac{x}{-1 - x}} \]
    4. Taylor expanded in x around inf 98.8%

      \[\leadsto \color{blue}{1} \]

    if -1 < x < 1

    1. Initial program 100.0%

      \[\frac{1}{x - 1} + \frac{x}{x + 1} \]
    2. Step-by-step derivation
      1. remove-double-neg100.0%

        \[\leadsto \frac{1}{x - 1} + \frac{\color{blue}{-\left(-x\right)}}{x + 1} \]
      2. distribute-frac-neg100.0%

        \[\leadsto \frac{1}{x - 1} + \color{blue}{\left(-\frac{-x}{x + 1}\right)} \]
      3. unsub-neg100.0%

        \[\leadsto \color{blue}{\frac{1}{x - 1} - \frac{-x}{x + 1}} \]
      4. sub-neg100.0%

        \[\leadsto \frac{1}{\color{blue}{x + \left(-1\right)}} - \frac{-x}{x + 1} \]
      5. metadata-eval100.0%

        \[\leadsto \frac{1}{x + \color{blue}{-1}} - \frac{-x}{x + 1} \]
      6. neg-mul-1100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{-1 \cdot x}}{x + 1} \]
      7. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{\left(-1\right)} \cdot x}{x + 1} \]
      8. *-commutative100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{x \cdot \left(-1\right)}}{x + 1} \]
      9. associate-/l*100.0%

        \[\leadsto \frac{1}{x + -1} - \color{blue}{\frac{x}{\frac{x + 1}{-1}}} \]
      10. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\color{blue}{-1}}} \]
      11. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\color{blue}{\frac{1}{-1}}}} \]
      12. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\frac{1}{\color{blue}{-1}}}} \]
      13. associate-/l*100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\frac{\left(x + 1\right) \cdot \left(-1\right)}{1}}} \]
      14. associate-*l/100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\frac{x + 1}{1} \cdot \left(-1\right)}} \]
      15. /-rgt-identity100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(x + 1\right)} \cdot \left(-1\right)} \]
      16. distribute-rgt1-in100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(-1\right) + x \cdot \left(-1\right)}} \]
      17. *-commutative100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{\left(-1\right) \cdot x}} \]
      18. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{-1} \cdot x} \]
      19. neg-mul-1100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{\left(-x\right)}} \]
      20. unsub-neg100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(-1\right) - x}} \]
      21. metadata-eval100.0%

        \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{-1} - x} \]
    3. Simplified100.0%

      \[\leadsto \color{blue}{\frac{1}{x + -1} - \frac{x}{-1 - x}} \]
    4. Taylor expanded in x around 0 99.3%

      \[\leadsto \frac{1}{x + -1} - \color{blue}{-1 \cdot x} \]
    5. Step-by-step derivation
      1. neg-mul-199.3%

        \[\leadsto \frac{1}{x + -1} - \color{blue}{\left(-x\right)} \]
    6. Simplified99.3%

      \[\leadsto \frac{1}{x + -1} - \color{blue}{\left(-x\right)} \]
    7. Taylor expanded in x around 0 99.2%

      \[\leadsto \color{blue}{\left(-1 \cdot x - 1\right)} - \left(-x\right) \]
    8. Step-by-step derivation
      1. sub-neg99.2%

        \[\leadsto \color{blue}{\left(-1 \cdot x + \left(-1\right)\right)} - \left(-x\right) \]
      2. neg-mul-199.2%

        \[\leadsto \left(\color{blue}{\left(-x\right)} + \left(-1\right)\right) - \left(-x\right) \]
      3. metadata-eval99.2%

        \[\leadsto \left(\left(-x\right) + \color{blue}{-1}\right) - \left(-x\right) \]
      4. +-commutative99.2%

        \[\leadsto \color{blue}{\left(-1 + \left(-x\right)\right)} - \left(-x\right) \]
      5. sub-neg99.2%

        \[\leadsto \color{blue}{\left(-1 - x\right)} - \left(-x\right) \]
    9. Simplified99.2%

      \[\leadsto \color{blue}{\left(-1 - x\right)} - \left(-x\right) \]
    10. Taylor expanded in x around 0 99.3%

      \[\leadsto \color{blue}{-1} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification99.0%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -1:\\ \;\;\;\;1\\ \mathbf{elif}\;x \leq 1:\\ \;\;\;\;-1\\ \mathbf{else}:\\ \;\;\;\;1\\ \end{array} \]

Alternative 5: 49.7% accurate, 11.0× speedup?

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

\\
-1
\end{array}
Derivation
  1. Initial program 100.0%

    \[\frac{1}{x - 1} + \frac{x}{x + 1} \]
  2. Step-by-step derivation
    1. remove-double-neg100.0%

      \[\leadsto \frac{1}{x - 1} + \frac{\color{blue}{-\left(-x\right)}}{x + 1} \]
    2. distribute-frac-neg100.0%

      \[\leadsto \frac{1}{x - 1} + \color{blue}{\left(-\frac{-x}{x + 1}\right)} \]
    3. unsub-neg100.0%

      \[\leadsto \color{blue}{\frac{1}{x - 1} - \frac{-x}{x + 1}} \]
    4. sub-neg100.0%

      \[\leadsto \frac{1}{\color{blue}{x + \left(-1\right)}} - \frac{-x}{x + 1} \]
    5. metadata-eval100.0%

      \[\leadsto \frac{1}{x + \color{blue}{-1}} - \frac{-x}{x + 1} \]
    6. neg-mul-1100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{-1 \cdot x}}{x + 1} \]
    7. metadata-eval100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{\left(-1\right)} \cdot x}{x + 1} \]
    8. *-commutative100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{\color{blue}{x \cdot \left(-1\right)}}{x + 1} \]
    9. associate-/l*100.0%

      \[\leadsto \frac{1}{x + -1} - \color{blue}{\frac{x}{\frac{x + 1}{-1}}} \]
    10. metadata-eval100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\color{blue}{-1}}} \]
    11. metadata-eval100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\color{blue}{\frac{1}{-1}}}} \]
    12. metadata-eval100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{x}{\frac{x + 1}{\frac{1}{\color{blue}{-1}}}} \]
    13. associate-/l*100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\frac{\left(x + 1\right) \cdot \left(-1\right)}{1}}} \]
    14. associate-*l/100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\frac{x + 1}{1} \cdot \left(-1\right)}} \]
    15. /-rgt-identity100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(x + 1\right)} \cdot \left(-1\right)} \]
    16. distribute-rgt1-in100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(-1\right) + x \cdot \left(-1\right)}} \]
    17. *-commutative100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{\left(-1\right) \cdot x}} \]
    18. metadata-eval100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{-1} \cdot x} \]
    19. neg-mul-1100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{x}{\left(-1\right) + \color{blue}{\left(-x\right)}} \]
    20. unsub-neg100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{\left(-1\right) - x}} \]
    21. metadata-eval100.0%

      \[\leadsto \frac{1}{x + -1} - \frac{x}{\color{blue}{-1} - x} \]
  3. Simplified100.0%

    \[\leadsto \color{blue}{\frac{1}{x + -1} - \frac{x}{-1 - x}} \]
  4. Taylor expanded in x around 0 50.1%

    \[\leadsto \frac{1}{x + -1} - \color{blue}{-1 \cdot x} \]
  5. Step-by-step derivation
    1. neg-mul-150.1%

      \[\leadsto \frac{1}{x + -1} - \color{blue}{\left(-x\right)} \]
  6. Simplified50.1%

    \[\leadsto \frac{1}{x + -1} - \color{blue}{\left(-x\right)} \]
  7. Taylor expanded in x around 0 50.0%

    \[\leadsto \color{blue}{\left(-1 \cdot x - 1\right)} - \left(-x\right) \]
  8. Step-by-step derivation
    1. sub-neg50.0%

      \[\leadsto \color{blue}{\left(-1 \cdot x + \left(-1\right)\right)} - \left(-x\right) \]
    2. neg-mul-150.0%

      \[\leadsto \left(\color{blue}{\left(-x\right)} + \left(-1\right)\right) - \left(-x\right) \]
    3. metadata-eval50.0%

      \[\leadsto \left(\left(-x\right) + \color{blue}{-1}\right) - \left(-x\right) \]
    4. +-commutative50.0%

      \[\leadsto \color{blue}{\left(-1 + \left(-x\right)\right)} - \left(-x\right) \]
    5. sub-neg50.0%

      \[\leadsto \color{blue}{\left(-1 - x\right)} - \left(-x\right) \]
  9. Simplified50.0%

    \[\leadsto \color{blue}{\left(-1 - x\right)} - \left(-x\right) \]
  10. Taylor expanded in x around 0 49.3%

    \[\leadsto \color{blue}{-1} \]
  11. Final simplification49.3%

    \[\leadsto -1 \]

Reproduce

?
herbie shell --seed 2023319 
(FPCore (x)
  :name "Asymptote B"
  :precision binary64
  (+ (/ 1.0 (- x 1.0)) (/ x (+ x 1.0))))