Numeric.SpecFunctions:invIncompleteGamma from math-functions-0.1.5.2, B

Percentage Accurate: 71.5% → 99.7%
Time: 11.1s
Alternatives: 9
Speedup: 1.0×

Specification

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

\\
1 - \log \left(1 - \frac{x - y}{1 - y}\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 9 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: 71.5% accurate, 1.0× speedup?

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

\\
1 - \log \left(1 - \frac{x - y}{1 - y}\right)
\end{array}

Alternative 1: 99.7% accurate, 0.5× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;y \leq -1100000:\\ \;\;\;\;\left(1 + \left(\frac{-1}{y} - \mathsf{log1p}\left(-x\right)\right)\right) - \log \left(\frac{-1}{y}\right)\\ \mathbf{elif}\;y \leq 10500000000000:\\ \;\;\;\;1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)\\ \mathbf{else}:\\ \;\;\;\;1 + \left(\log y - \log \left(-1 + x\right)\right)\\ \end{array} \end{array} \]
(FPCore (x y)
 :precision binary64
 (if (<= y -1100000.0)
   (- (+ 1.0 (- (/ -1.0 y) (log1p (- x)))) (log (/ -1.0 y)))
   (if (<= y 10500000000000.0)
     (- 1.0 (log1p (/ (- x y) (+ y -1.0))))
     (+ 1.0 (- (log y) (log (+ -1.0 x)))))))
double code(double x, double y) {
	double tmp;
	if (y <= -1100000.0) {
		tmp = (1.0 + ((-1.0 / y) - log1p(-x))) - log((-1.0 / y));
	} else if (y <= 10500000000000.0) {
		tmp = 1.0 - log1p(((x - y) / (y + -1.0)));
	} else {
		tmp = 1.0 + (log(y) - log((-1.0 + x)));
	}
	return tmp;
}
public static double code(double x, double y) {
	double tmp;
	if (y <= -1100000.0) {
		tmp = (1.0 + ((-1.0 / y) - Math.log1p(-x))) - Math.log((-1.0 / y));
	} else if (y <= 10500000000000.0) {
		tmp = 1.0 - Math.log1p(((x - y) / (y + -1.0)));
	} else {
		tmp = 1.0 + (Math.log(y) - Math.log((-1.0 + x)));
	}
	return tmp;
}
def code(x, y):
	tmp = 0
	if y <= -1100000.0:
		tmp = (1.0 + ((-1.0 / y) - math.log1p(-x))) - math.log((-1.0 / y))
	elif y <= 10500000000000.0:
		tmp = 1.0 - math.log1p(((x - y) / (y + -1.0)))
	else:
		tmp = 1.0 + (math.log(y) - math.log((-1.0 + x)))
	return tmp
function code(x, y)
	tmp = 0.0
	if (y <= -1100000.0)
		tmp = Float64(Float64(1.0 + Float64(Float64(-1.0 / y) - log1p(Float64(-x)))) - log(Float64(-1.0 / y)));
	elseif (y <= 10500000000000.0)
		tmp = Float64(1.0 - log1p(Float64(Float64(x - y) / Float64(y + -1.0))));
	else
		tmp = Float64(1.0 + Float64(log(y) - log(Float64(-1.0 + x))));
	end
	return tmp
end
code[x_, y_] := If[LessEqual[y, -1100000.0], N[(N[(1.0 + N[(N[(-1.0 / y), $MachinePrecision] - N[Log[1 + (-x)], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] - N[Log[N[(-1.0 / y), $MachinePrecision]], $MachinePrecision]), $MachinePrecision], If[LessEqual[y, 10500000000000.0], N[(1.0 - N[Log[1 + N[(N[(x - y), $MachinePrecision] / N[(y + -1.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision], N[(1.0 + N[(N[Log[y], $MachinePrecision] - N[Log[N[(-1.0 + x), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;y \leq -1100000:\\
\;\;\;\;\left(1 + \left(\frac{-1}{y} - \mathsf{log1p}\left(-x\right)\right)\right) - \log \left(\frac{-1}{y}\right)\\

\mathbf{elif}\;y \leq 10500000000000:\\
\;\;\;\;1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)\\

\mathbf{else}:\\
\;\;\;\;1 + \left(\log y - \log \left(-1 + x\right)\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if y < -1.1e6

    1. Initial program 23.0%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg23.0%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define23.0%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac223.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub023.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-23.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval23.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative23.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified23.0%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing
    5. Taylor expanded in y around -inf 99.6%

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

      \[\leadsto \color{blue}{\left(1 + \left(\frac{-1}{y} - \mathsf{log1p}\left(-x\right)\right)\right) - \log \left(\frac{-1}{y}\right)} \]

    if -1.1e6 < y < 1.05e13

    1. Initial program 100.0%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg100.0%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define100.0%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac2100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub0100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified100.0%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing

    if 1.05e13 < y

    1. Initial program 55.6%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg55.6%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define55.6%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac255.6%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub055.6%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-55.6%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval55.6%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative55.6%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified55.6%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing
    5. Taylor expanded in y around inf 98.0%

      \[\leadsto 1 - \color{blue}{\left(\log \left(x - 1\right) + \log \left(\frac{1}{y}\right)\right)} \]
    6. Step-by-step derivation
      1. log-rec98.0%

        \[\leadsto 1 - \left(\log \left(x - 1\right) + \color{blue}{\left(-\log y\right)}\right) \]
      2. unsub-neg98.0%

        \[\leadsto 1 - \color{blue}{\left(\log \left(x - 1\right) - \log y\right)} \]
      3. sub-neg98.0%

        \[\leadsto 1 - \left(\log \color{blue}{\left(x + \left(-1\right)\right)} - \log y\right) \]
      4. metadata-eval98.0%

        \[\leadsto 1 - \left(\log \left(x + \color{blue}{-1}\right) - \log y\right) \]
    7. Simplified98.0%

      \[\leadsto 1 - \color{blue}{\left(\log \left(x + -1\right) - \log y\right)} \]
  3. Recombined 3 regimes into one program.
  4. Final simplification99.7%

    \[\leadsto \begin{array}{l} \mathbf{if}\;y \leq -1100000:\\ \;\;\;\;\left(1 + \left(\frac{-1}{y} - \mathsf{log1p}\left(-x\right)\right)\right) - \log \left(\frac{-1}{y}\right)\\ \mathbf{elif}\;y \leq 10500000000000:\\ \;\;\;\;1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)\\ \mathbf{else}:\\ \;\;\;\;1 + \left(\log y - \log \left(-1 + x\right)\right)\\ \end{array} \]
  5. Add Preprocessing

Alternative 2: 99.6% accurate, 0.5× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;y \leq -4500000000:\\ \;\;\;\;1 - \left(\mathsf{log1p}\left(-x\right) + \log \left(\frac{-1}{y}\right)\right)\\ \mathbf{elif}\;y \leq 2.25 \cdot 10^{+21}:\\ \;\;\;\;1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)\\ \mathbf{else}:\\ \;\;\;\;1 + \left(\log y - \log \left(-1 + x\right)\right)\\ \end{array} \end{array} \]
(FPCore (x y)
 :precision binary64
 (if (<= y -4500000000.0)
   (- 1.0 (+ (log1p (- x)) (log (/ -1.0 y))))
   (if (<= y 2.25e+21)
     (- 1.0 (log1p (/ (- x y) (+ y -1.0))))
     (+ 1.0 (- (log y) (log (+ -1.0 x)))))))
double code(double x, double y) {
	double tmp;
	if (y <= -4500000000.0) {
		tmp = 1.0 - (log1p(-x) + log((-1.0 / y)));
	} else if (y <= 2.25e+21) {
		tmp = 1.0 - log1p(((x - y) / (y + -1.0)));
	} else {
		tmp = 1.0 + (log(y) - log((-1.0 + x)));
	}
	return tmp;
}
public static double code(double x, double y) {
	double tmp;
	if (y <= -4500000000.0) {
		tmp = 1.0 - (Math.log1p(-x) + Math.log((-1.0 / y)));
	} else if (y <= 2.25e+21) {
		tmp = 1.0 - Math.log1p(((x - y) / (y + -1.0)));
	} else {
		tmp = 1.0 + (Math.log(y) - Math.log((-1.0 + x)));
	}
	return tmp;
}
def code(x, y):
	tmp = 0
	if y <= -4500000000.0:
		tmp = 1.0 - (math.log1p(-x) + math.log((-1.0 / y)))
	elif y <= 2.25e+21:
		tmp = 1.0 - math.log1p(((x - y) / (y + -1.0)))
	else:
		tmp = 1.0 + (math.log(y) - math.log((-1.0 + x)))
	return tmp
function code(x, y)
	tmp = 0.0
	if (y <= -4500000000.0)
		tmp = Float64(1.0 - Float64(log1p(Float64(-x)) + log(Float64(-1.0 / y))));
	elseif (y <= 2.25e+21)
		tmp = Float64(1.0 - log1p(Float64(Float64(x - y) / Float64(y + -1.0))));
	else
		tmp = Float64(1.0 + Float64(log(y) - log(Float64(-1.0 + x))));
	end
	return tmp
end
code[x_, y_] := If[LessEqual[y, -4500000000.0], N[(1.0 - N[(N[Log[1 + (-x)], $MachinePrecision] + N[Log[N[(-1.0 / y), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision], If[LessEqual[y, 2.25e+21], N[(1.0 - N[Log[1 + N[(N[(x - y), $MachinePrecision] / N[(y + -1.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision], N[(1.0 + N[(N[Log[y], $MachinePrecision] - N[Log[N[(-1.0 + x), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;y \leq -4500000000:\\
\;\;\;\;1 - \left(\mathsf{log1p}\left(-x\right) + \log \left(\frac{-1}{y}\right)\right)\\

\mathbf{elif}\;y \leq 2.25 \cdot 10^{+21}:\\
\;\;\;\;1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)\\

\mathbf{else}:\\
\;\;\;\;1 + \left(\log y - \log \left(-1 + x\right)\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if y < -4.5e9

    1. Initial program 23.0%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg23.0%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define23.0%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac223.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub023.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-23.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval23.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative23.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified23.0%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing
    5. Taylor expanded in y around -inf 99.2%

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

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

        \[\leadsto 1 - \left(\log \left(-1 \cdot \left(x + \color{blue}{-1}\right)\right) + \log \left(\frac{-1}{y}\right)\right) \]
      3. distribute-lft-in99.2%

        \[\leadsto 1 - \left(\log \color{blue}{\left(-1 \cdot x + -1 \cdot -1\right)} + \log \left(\frac{-1}{y}\right)\right) \]
      4. metadata-eval99.2%

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

        \[\leadsto 1 - \left(\log \color{blue}{\left(1 + -1 \cdot x\right)} + \log \left(\frac{-1}{y}\right)\right) \]
      6. log1p-define99.2%

        \[\leadsto 1 - \left(\color{blue}{\mathsf{log1p}\left(-1 \cdot x\right)} + \log \left(\frac{-1}{y}\right)\right) \]
      7. mul-1-neg99.2%

        \[\leadsto 1 - \left(\mathsf{log1p}\left(\color{blue}{-x}\right) + \log \left(\frac{-1}{y}\right)\right) \]
    7. Simplified99.2%

      \[\leadsto 1 - \color{blue}{\left(\mathsf{log1p}\left(-x\right) + \log \left(\frac{-1}{y}\right)\right)} \]

    if -4.5e9 < y < 2.25e21

    1. Initial program 100.0%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg100.0%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define100.0%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac2100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub0100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified100.0%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing

    if 2.25e21 < y

    1. Initial program 55.6%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg55.6%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define55.6%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac255.6%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub055.6%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-55.6%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval55.6%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative55.6%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified55.6%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing
    5. Taylor expanded in y around inf 98.0%

      \[\leadsto 1 - \color{blue}{\left(\log \left(x - 1\right) + \log \left(\frac{1}{y}\right)\right)} \]
    6. Step-by-step derivation
      1. log-rec98.0%

        \[\leadsto 1 - \left(\log \left(x - 1\right) + \color{blue}{\left(-\log y\right)}\right) \]
      2. unsub-neg98.0%

        \[\leadsto 1 - \color{blue}{\left(\log \left(x - 1\right) - \log y\right)} \]
      3. sub-neg98.0%

        \[\leadsto 1 - \left(\log \color{blue}{\left(x + \left(-1\right)\right)} - \log y\right) \]
      4. metadata-eval98.0%

        \[\leadsto 1 - \left(\log \left(x + \color{blue}{-1}\right) - \log y\right) \]
    7. Simplified98.0%

      \[\leadsto 1 - \color{blue}{\left(\log \left(x + -1\right) - \log y\right)} \]
  3. Recombined 3 regimes into one program.
  4. Final simplification99.6%

    \[\leadsto \begin{array}{l} \mathbf{if}\;y \leq -4500000000:\\ \;\;\;\;1 - \left(\mathsf{log1p}\left(-x\right) + \log \left(\frac{-1}{y}\right)\right)\\ \mathbf{elif}\;y \leq 2.25 \cdot 10^{+21}:\\ \;\;\;\;1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)\\ \mathbf{else}:\\ \;\;\;\;1 + \left(\log y - \log \left(-1 + x\right)\right)\\ \end{array} \]
  5. Add Preprocessing

Alternative 3: 89.9% accurate, 0.9× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;\frac{x - y}{1 - y} \leq 0.2:\\ \;\;\;\;1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)\\ \mathbf{else}:\\ \;\;\;\;1 + \left(\frac{-1}{y} - \log \left(\frac{-1}{y}\right)\right)\\ \end{array} \end{array} \]
(FPCore (x y)
 :precision binary64
 (if (<= (/ (- x y) (- 1.0 y)) 0.2)
   (- 1.0 (log1p (/ (- x y) (+ y -1.0))))
   (+ 1.0 (- (/ -1.0 y) (log (/ -1.0 y))))))
double code(double x, double y) {
	double tmp;
	if (((x - y) / (1.0 - y)) <= 0.2) {
		tmp = 1.0 - log1p(((x - y) / (y + -1.0)));
	} else {
		tmp = 1.0 + ((-1.0 / y) - log((-1.0 / y)));
	}
	return tmp;
}
public static double code(double x, double y) {
	double tmp;
	if (((x - y) / (1.0 - y)) <= 0.2) {
		tmp = 1.0 - Math.log1p(((x - y) / (y + -1.0)));
	} else {
		tmp = 1.0 + ((-1.0 / y) - Math.log((-1.0 / y)));
	}
	return tmp;
}
def code(x, y):
	tmp = 0
	if ((x - y) / (1.0 - y)) <= 0.2:
		tmp = 1.0 - math.log1p(((x - y) / (y + -1.0)))
	else:
		tmp = 1.0 + ((-1.0 / y) - math.log((-1.0 / y)))
	return tmp
function code(x, y)
	tmp = 0.0
	if (Float64(Float64(x - y) / Float64(1.0 - y)) <= 0.2)
		tmp = Float64(1.0 - log1p(Float64(Float64(x - y) / Float64(y + -1.0))));
	else
		tmp = Float64(1.0 + Float64(Float64(-1.0 / y) - log(Float64(-1.0 / y))));
	end
	return tmp
end
code[x_, y_] := If[LessEqual[N[(N[(x - y), $MachinePrecision] / N[(1.0 - y), $MachinePrecision]), $MachinePrecision], 0.2], N[(1.0 - N[Log[1 + N[(N[(x - y), $MachinePrecision] / N[(y + -1.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision], N[(1.0 + N[(N[(-1.0 / y), $MachinePrecision] - N[Log[N[(-1.0 / y), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;\frac{x - y}{1 - y} \leq 0.2:\\
\;\;\;\;1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)\\

\mathbf{else}:\\
\;\;\;\;1 + \left(\frac{-1}{y} - \log \left(\frac{-1}{y}\right)\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (/.f64 (-.f64 x y) (-.f64 #s(literal 1 binary64) y)) < 0.20000000000000001

    1. Initial program 100.0%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg100.0%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define100.0%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac2100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub0100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative100.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified100.0%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing

    if 0.20000000000000001 < (/.f64 (-.f64 x y) (-.f64 #s(literal 1 binary64) y))

    1. Initial program 4.5%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg4.5%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define4.5%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac24.5%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub04.5%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-4.5%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval4.5%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative4.5%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified4.5%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing
    5. Taylor expanded in x around 0 4.5%

      \[\leadsto 1 - \color{blue}{\log \left(1 - \frac{y}{y - 1}\right)} \]
    6. Step-by-step derivation
      1. sub-neg4.5%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{y}{y - 1}\right)\right)} \]
      2. mul-1-neg4.5%

        \[\leadsto 1 - \log \left(1 + \color{blue}{-1 \cdot \frac{y}{y - 1}}\right) \]
      3. sub-neg4.5%

        \[\leadsto 1 - \log \left(1 + -1 \cdot \frac{y}{\color{blue}{y + \left(-1\right)}}\right) \]
      4. metadata-eval4.5%

        \[\leadsto 1 - \log \left(1 + -1 \cdot \frac{y}{y + \color{blue}{-1}}\right) \]
      5. neg-mul-14.5%

        \[\leadsto 1 - \log \left(1 + \color{blue}{\left(-\frac{y}{y + -1}\right)}\right) \]
      6. log1p-define4.5%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{y}{y + -1}\right)} \]
      7. distribute-neg-frac24.5%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{y}{-\left(y + -1\right)}}\right) \]
      8. +-commutative4.5%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{-\color{blue}{\left(-1 + y\right)}}\right) \]
      9. distribute-neg-in4.5%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{\left(--1\right) + \left(-y\right)}}\right) \]
      10. metadata-eval4.5%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{1} + \left(-y\right)}\right) \]
      11. unsub-neg4.5%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{1 - y}}\right) \]
    7. Simplified4.5%

      \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(\frac{y}{1 - y}\right)} \]
    8. Taylor expanded in y around -inf 76.1%

      \[\leadsto 1 - \color{blue}{\left(\log \left(\frac{-1}{y}\right) + \frac{1}{y}\right)} \]
    9. Step-by-step derivation
      1. +-commutative76.1%

        \[\leadsto 1 - \color{blue}{\left(\frac{1}{y} + \log \left(\frac{-1}{y}\right)\right)} \]
    10. Simplified76.1%

      \[\leadsto 1 - \color{blue}{\left(\frac{1}{y} + \log \left(\frac{-1}{y}\right)\right)} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification93.4%

    \[\leadsto \begin{array}{l} \mathbf{if}\;\frac{x - y}{1 - y} \leq 0.2:\\ \;\;\;\;1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)\\ \mathbf{else}:\\ \;\;\;\;1 + \left(\frac{-1}{y} - \log \left(\frac{-1}{y}\right)\right)\\ \end{array} \]
  5. Add Preprocessing

Alternative 4: 86.0% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;y \leq -2.45 \cdot 10^{+20}:\\ \;\;\;\;1 - \log \left(\frac{-1}{y}\right)\\ \mathbf{else}:\\ \;\;\;\;1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)\\ \end{array} \end{array} \]
(FPCore (x y)
 :precision binary64
 (if (<= y -2.45e+20)
   (- 1.0 (log (/ -1.0 y)))
   (- 1.0 (log1p (/ (- x y) (+ y -1.0))))))
double code(double x, double y) {
	double tmp;
	if (y <= -2.45e+20) {
		tmp = 1.0 - log((-1.0 / y));
	} else {
		tmp = 1.0 - log1p(((x - y) / (y + -1.0)));
	}
	return tmp;
}
public static double code(double x, double y) {
	double tmp;
	if (y <= -2.45e+20) {
		tmp = 1.0 - Math.log((-1.0 / y));
	} else {
		tmp = 1.0 - Math.log1p(((x - y) / (y + -1.0)));
	}
	return tmp;
}
def code(x, y):
	tmp = 0
	if y <= -2.45e+20:
		tmp = 1.0 - math.log((-1.0 / y))
	else:
		tmp = 1.0 - math.log1p(((x - y) / (y + -1.0)))
	return tmp
function code(x, y)
	tmp = 0.0
	if (y <= -2.45e+20)
		tmp = Float64(1.0 - log(Float64(-1.0 / y)));
	else
		tmp = Float64(1.0 - log1p(Float64(Float64(x - y) / Float64(y + -1.0))));
	end
	return tmp
end
code[x_, y_] := If[LessEqual[y, -2.45e+20], N[(1.0 - N[Log[N[(-1.0 / y), $MachinePrecision]], $MachinePrecision]), $MachinePrecision], N[(1.0 - N[Log[1 + N[(N[(x - y), $MachinePrecision] / N[(y + -1.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;y \leq -2.45 \cdot 10^{+20}:\\
\;\;\;\;1 - \log \left(\frac{-1}{y}\right)\\

\mathbf{else}:\\
\;\;\;\;1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if y < -2.45e20

    1. Initial program 20.0%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg20.0%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define20.0%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac220.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub020.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-20.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval20.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative20.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified20.0%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing
    5. Taylor expanded in x around 0 2.7%

      \[\leadsto 1 - \color{blue}{\log \left(1 - \frac{y}{y - 1}\right)} \]
    6. Step-by-step derivation
      1. sub-neg2.7%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{y}{y - 1}\right)\right)} \]
      2. mul-1-neg2.7%

        \[\leadsto 1 - \log \left(1 + \color{blue}{-1 \cdot \frac{y}{y - 1}}\right) \]
      3. sub-neg2.7%

        \[\leadsto 1 - \log \left(1 + -1 \cdot \frac{y}{\color{blue}{y + \left(-1\right)}}\right) \]
      4. metadata-eval2.7%

        \[\leadsto 1 - \log \left(1 + -1 \cdot \frac{y}{y + \color{blue}{-1}}\right) \]
      5. neg-mul-12.7%

        \[\leadsto 1 - \log \left(1 + \color{blue}{\left(-\frac{y}{y + -1}\right)}\right) \]
      6. log1p-define2.7%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{y}{y + -1}\right)} \]
      7. distribute-neg-frac22.7%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{y}{-\left(y + -1\right)}}\right) \]
      8. +-commutative2.7%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{-\color{blue}{\left(-1 + y\right)}}\right) \]
      9. distribute-neg-in2.7%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{\left(--1\right) + \left(-y\right)}}\right) \]
      10. metadata-eval2.7%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{1} + \left(-y\right)}\right) \]
      11. unsub-neg2.7%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{1 - y}}\right) \]
    7. Simplified2.7%

      \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(\frac{y}{1 - y}\right)} \]
    8. Taylor expanded in y around -inf 74.6%

      \[\leadsto 1 - \color{blue}{\log \left(\frac{-1}{y}\right)} \]

    if -2.45e20 < y

    1. Initial program 93.7%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg93.7%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define93.8%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac293.8%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub093.8%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-93.8%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval93.8%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative93.8%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified93.8%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing
  3. Recombined 2 regimes into one program.
  4. Final simplification88.6%

    \[\leadsto \begin{array}{l} \mathbf{if}\;y \leq -2.45 \cdot 10^{+20}:\\ \;\;\;\;1 - \log \left(\frac{-1}{y}\right)\\ \mathbf{else}:\\ \;\;\;\;1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)\\ \end{array} \]
  5. Add Preprocessing

Alternative 5: 84.7% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;y \leq -2.65 \cdot 10^{+22}:\\ \;\;\;\;1 - \log \left(\frac{-1}{y}\right)\\ \mathbf{else}:\\ \;\;\;\;1 - \mathsf{log1p}\left(\frac{x}{y + -1}\right)\\ \end{array} \end{array} \]
(FPCore (x y)
 :precision binary64
 (if (<= y -2.65e+22)
   (- 1.0 (log (/ -1.0 y)))
   (- 1.0 (log1p (/ x (+ y -1.0))))))
double code(double x, double y) {
	double tmp;
	if (y <= -2.65e+22) {
		tmp = 1.0 - log((-1.0 / y));
	} else {
		tmp = 1.0 - log1p((x / (y + -1.0)));
	}
	return tmp;
}
public static double code(double x, double y) {
	double tmp;
	if (y <= -2.65e+22) {
		tmp = 1.0 - Math.log((-1.0 / y));
	} else {
		tmp = 1.0 - Math.log1p((x / (y + -1.0)));
	}
	return tmp;
}
def code(x, y):
	tmp = 0
	if y <= -2.65e+22:
		tmp = 1.0 - math.log((-1.0 / y))
	else:
		tmp = 1.0 - math.log1p((x / (y + -1.0)))
	return tmp
function code(x, y)
	tmp = 0.0
	if (y <= -2.65e+22)
		tmp = Float64(1.0 - log(Float64(-1.0 / y)));
	else
		tmp = Float64(1.0 - log1p(Float64(x / Float64(y + -1.0))));
	end
	return tmp
end
code[x_, y_] := If[LessEqual[y, -2.65e+22], N[(1.0 - N[Log[N[(-1.0 / y), $MachinePrecision]], $MachinePrecision]), $MachinePrecision], N[(1.0 - N[Log[1 + N[(x / N[(y + -1.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;y \leq -2.65 \cdot 10^{+22}:\\
\;\;\;\;1 - \log \left(\frac{-1}{y}\right)\\

\mathbf{else}:\\
\;\;\;\;1 - \mathsf{log1p}\left(\frac{x}{y + -1}\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if y < -2.6499999999999999e22

    1. Initial program 20.0%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg20.0%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define20.0%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac220.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub020.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-20.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval20.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative20.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified20.0%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing
    5. Taylor expanded in x around 0 2.7%

      \[\leadsto 1 - \color{blue}{\log \left(1 - \frac{y}{y - 1}\right)} \]
    6. Step-by-step derivation
      1. sub-neg2.7%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{y}{y - 1}\right)\right)} \]
      2. mul-1-neg2.7%

        \[\leadsto 1 - \log \left(1 + \color{blue}{-1 \cdot \frac{y}{y - 1}}\right) \]
      3. sub-neg2.7%

        \[\leadsto 1 - \log \left(1 + -1 \cdot \frac{y}{\color{blue}{y + \left(-1\right)}}\right) \]
      4. metadata-eval2.7%

        \[\leadsto 1 - \log \left(1 + -1 \cdot \frac{y}{y + \color{blue}{-1}}\right) \]
      5. neg-mul-12.7%

        \[\leadsto 1 - \log \left(1 + \color{blue}{\left(-\frac{y}{y + -1}\right)}\right) \]
      6. log1p-define2.7%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{y}{y + -1}\right)} \]
      7. distribute-neg-frac22.7%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{y}{-\left(y + -1\right)}}\right) \]
      8. +-commutative2.7%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{-\color{blue}{\left(-1 + y\right)}}\right) \]
      9. distribute-neg-in2.7%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{\left(--1\right) + \left(-y\right)}}\right) \]
      10. metadata-eval2.7%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{1} + \left(-y\right)}\right) \]
      11. unsub-neg2.7%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{1 - y}}\right) \]
    7. Simplified2.7%

      \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(\frac{y}{1 - y}\right)} \]
    8. Taylor expanded in y around -inf 74.6%

      \[\leadsto 1 - \color{blue}{\log \left(\frac{-1}{y}\right)} \]

    if -2.6499999999999999e22 < y

    1. Initial program 93.7%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg93.7%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define93.8%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac293.8%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub093.8%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-93.8%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval93.8%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative93.8%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified93.8%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing
    5. Taylor expanded in x around inf 92.5%

      \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x}{y - 1}}\right) \]
  3. Recombined 2 regimes into one program.
  4. Final simplification87.6%

    \[\leadsto \begin{array}{l} \mathbf{if}\;y \leq -2.65 \cdot 10^{+22}:\\ \;\;\;\;1 - \log \left(\frac{-1}{y}\right)\\ \mathbf{else}:\\ \;\;\;\;1 - \mathsf{log1p}\left(\frac{x}{y + -1}\right)\\ \end{array} \]
  5. Add Preprocessing

Alternative 6: 79.4% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;y \leq -30:\\ \;\;\;\;1 - \log \left(\frac{-1}{y}\right)\\ \mathbf{else}:\\ \;\;\;\;\left(1 - y\right) - \mathsf{log1p}\left(-x\right)\\ \end{array} \end{array} \]
(FPCore (x y)
 :precision binary64
 (if (<= y -30.0) (- 1.0 (log (/ -1.0 y))) (- (- 1.0 y) (log1p (- x)))))
double code(double x, double y) {
	double tmp;
	if (y <= -30.0) {
		tmp = 1.0 - log((-1.0 / y));
	} else {
		tmp = (1.0 - y) - log1p(-x);
	}
	return tmp;
}
public static double code(double x, double y) {
	double tmp;
	if (y <= -30.0) {
		tmp = 1.0 - Math.log((-1.0 / y));
	} else {
		tmp = (1.0 - y) - Math.log1p(-x);
	}
	return tmp;
}
def code(x, y):
	tmp = 0
	if y <= -30.0:
		tmp = 1.0 - math.log((-1.0 / y))
	else:
		tmp = (1.0 - y) - math.log1p(-x)
	return tmp
function code(x, y)
	tmp = 0.0
	if (y <= -30.0)
		tmp = Float64(1.0 - log(Float64(-1.0 / y)));
	else
		tmp = Float64(Float64(1.0 - y) - log1p(Float64(-x)));
	end
	return tmp
end
code[x_, y_] := If[LessEqual[y, -30.0], N[(1.0 - N[Log[N[(-1.0 / y), $MachinePrecision]], $MachinePrecision]), $MachinePrecision], N[(N[(1.0 - y), $MachinePrecision] - N[Log[1 + (-x)], $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;y \leq -30:\\
\;\;\;\;1 - \log \left(\frac{-1}{y}\right)\\

\mathbf{else}:\\
\;\;\;\;\left(1 - y\right) - \mathsf{log1p}\left(-x\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if y < -30

    1. Initial program 25.0%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg25.0%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define25.0%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac225.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub025.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-25.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval25.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative25.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified25.0%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing
    5. Taylor expanded in x around 0 3.9%

      \[\leadsto 1 - \color{blue}{\log \left(1 - \frac{y}{y - 1}\right)} \]
    6. Step-by-step derivation
      1. sub-neg3.9%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{y}{y - 1}\right)\right)} \]
      2. mul-1-neg3.9%

        \[\leadsto 1 - \log \left(1 + \color{blue}{-1 \cdot \frac{y}{y - 1}}\right) \]
      3. sub-neg3.9%

        \[\leadsto 1 - \log \left(1 + -1 \cdot \frac{y}{\color{blue}{y + \left(-1\right)}}\right) \]
      4. metadata-eval3.9%

        \[\leadsto 1 - \log \left(1 + -1 \cdot \frac{y}{y + \color{blue}{-1}}\right) \]
      5. neg-mul-13.9%

        \[\leadsto 1 - \log \left(1 + \color{blue}{\left(-\frac{y}{y + -1}\right)}\right) \]
      6. log1p-define3.9%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{y}{y + -1}\right)} \]
      7. distribute-neg-frac23.9%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{y}{-\left(y + -1\right)}}\right) \]
      8. +-commutative3.9%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{-\color{blue}{\left(-1 + y\right)}}\right) \]
      9. distribute-neg-in3.9%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{\left(--1\right) + \left(-y\right)}}\right) \]
      10. metadata-eval3.9%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{1} + \left(-y\right)}\right) \]
      11. unsub-neg3.9%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{1 - y}}\right) \]
    7. Simplified3.9%

      \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(\frac{y}{1 - y}\right)} \]
    8. Taylor expanded in y around -inf 71.0%

      \[\leadsto 1 - \color{blue}{\log \left(\frac{-1}{y}\right)} \]

    if -30 < y

    1. Initial program 94.1%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg94.1%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define94.1%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac294.1%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub094.1%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-94.1%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval94.1%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative94.1%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified94.1%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing
    5. Taylor expanded in y around 0 85.1%

      \[\leadsto \color{blue}{\left(1 + y \cdot \left(\frac{x}{1 + -1 \cdot x} - \frac{1}{1 + -1 \cdot x}\right)\right) - \log \left(1 + -1 \cdot x\right)} \]
    6. Simplified85.1%

      \[\leadsto \color{blue}{\left(1 - y\right) - \mathsf{log1p}\left(-x\right)} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification81.0%

    \[\leadsto \begin{array}{l} \mathbf{if}\;y \leq -30:\\ \;\;\;\;1 - \log \left(\frac{-1}{y}\right)\\ \mathbf{else}:\\ \;\;\;\;\left(1 - y\right) - \mathsf{log1p}\left(-x\right)\\ \end{array} \]
  5. Add Preprocessing

Alternative 7: 78.8% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;y \leq -1100000:\\ \;\;\;\;1 - \log \left(\frac{-1}{y}\right)\\ \mathbf{else}:\\ \;\;\;\;1 - \mathsf{log1p}\left(-x\right)\\ \end{array} \end{array} \]
(FPCore (x y)
 :precision binary64
 (if (<= y -1100000.0) (- 1.0 (log (/ -1.0 y))) (- 1.0 (log1p (- x)))))
double code(double x, double y) {
	double tmp;
	if (y <= -1100000.0) {
		tmp = 1.0 - log((-1.0 / y));
	} else {
		tmp = 1.0 - log1p(-x);
	}
	return tmp;
}
public static double code(double x, double y) {
	double tmp;
	if (y <= -1100000.0) {
		tmp = 1.0 - Math.log((-1.0 / y));
	} else {
		tmp = 1.0 - Math.log1p(-x);
	}
	return tmp;
}
def code(x, y):
	tmp = 0
	if y <= -1100000.0:
		tmp = 1.0 - math.log((-1.0 / y))
	else:
		tmp = 1.0 - math.log1p(-x)
	return tmp
function code(x, y)
	tmp = 0.0
	if (y <= -1100000.0)
		tmp = Float64(1.0 - log(Float64(-1.0 / y)));
	else
		tmp = Float64(1.0 - log1p(Float64(-x)));
	end
	return tmp
end
code[x_, y_] := If[LessEqual[y, -1100000.0], N[(1.0 - N[Log[N[(-1.0 / y), $MachinePrecision]], $MachinePrecision]), $MachinePrecision], N[(1.0 - N[Log[1 + (-x)], $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;y \leq -1100000:\\
\;\;\;\;1 - \log \left(\frac{-1}{y}\right)\\

\mathbf{else}:\\
\;\;\;\;1 - \mathsf{log1p}\left(-x\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if y < -1.1e6

    1. Initial program 23.0%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg23.0%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define23.0%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac223.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub023.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-23.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval23.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative23.0%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified23.0%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing
    5. Taylor expanded in x around 0 3.9%

      \[\leadsto 1 - \color{blue}{\log \left(1 - \frac{y}{y - 1}\right)} \]
    6. Step-by-step derivation
      1. sub-neg3.9%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{y}{y - 1}\right)\right)} \]
      2. mul-1-neg3.9%

        \[\leadsto 1 - \log \left(1 + \color{blue}{-1 \cdot \frac{y}{y - 1}}\right) \]
      3. sub-neg3.9%

        \[\leadsto 1 - \log \left(1 + -1 \cdot \frac{y}{\color{blue}{y + \left(-1\right)}}\right) \]
      4. metadata-eval3.9%

        \[\leadsto 1 - \log \left(1 + -1 \cdot \frac{y}{y + \color{blue}{-1}}\right) \]
      5. neg-mul-13.9%

        \[\leadsto 1 - \log \left(1 + \color{blue}{\left(-\frac{y}{y + -1}\right)}\right) \]
      6. log1p-define3.9%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{y}{y + -1}\right)} \]
      7. distribute-neg-frac23.9%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{y}{-\left(y + -1\right)}}\right) \]
      8. +-commutative3.9%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{-\color{blue}{\left(-1 + y\right)}}\right) \]
      9. distribute-neg-in3.9%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{\left(--1\right) + \left(-y\right)}}\right) \]
      10. metadata-eval3.9%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{1} + \left(-y\right)}\right) \]
      11. unsub-neg3.9%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{1 - y}}\right) \]
    7. Simplified3.9%

      \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(\frac{y}{1 - y}\right)} \]
    8. Taylor expanded in y around -inf 72.9%

      \[\leadsto 1 - \color{blue}{\log \left(\frac{-1}{y}\right)} \]

    if -1.1e6 < y

    1. Initial program 94.1%

      \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
    2. Step-by-step derivation
      1. sub-neg94.1%

        \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
      2. log1p-define94.2%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
      3. distribute-neg-frac294.2%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
      4. neg-sub094.2%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
      5. associate--r-94.2%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
      6. metadata-eval94.2%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
      7. +-commutative94.2%

        \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
    3. Simplified94.2%

      \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
    4. Add Preprocessing
    5. Taylor expanded in y around 0 83.6%

      \[\leadsto 1 - \color{blue}{\log \left(1 + -1 \cdot x\right)} \]
    6. Step-by-step derivation
      1. log1p-define83.7%

        \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-1 \cdot x\right)} \]
      2. mul-1-neg83.7%

        \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{-x}\right) \]
    7. Simplified83.7%

      \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-x\right)} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification80.6%

    \[\leadsto \begin{array}{l} \mathbf{if}\;y \leq -1100000:\\ \;\;\;\;1 - \log \left(\frac{-1}{y}\right)\\ \mathbf{else}:\\ \;\;\;\;1 - \mathsf{log1p}\left(-x\right)\\ \end{array} \]
  5. Add Preprocessing

Alternative 8: 62.0% accurate, 1.1× speedup?

\[\begin{array}{l} \\ 1 - \mathsf{log1p}\left(-x\right) \end{array} \]
(FPCore (x y) :precision binary64 (- 1.0 (log1p (- x))))
double code(double x, double y) {
	return 1.0 - log1p(-x);
}
public static double code(double x, double y) {
	return 1.0 - Math.log1p(-x);
}
def code(x, y):
	return 1.0 - math.log1p(-x)
function code(x, y)
	return Float64(1.0 - log1p(Float64(-x)))
end
code[x_, y_] := N[(1.0 - N[Log[1 + (-x)], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
1 - \mathsf{log1p}\left(-x\right)
\end{array}
Derivation
  1. Initial program 73.9%

    \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
  2. Step-by-step derivation
    1. sub-neg73.9%

      \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
    2. log1p-define73.9%

      \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
    3. distribute-neg-frac273.9%

      \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
    4. neg-sub073.9%

      \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
    5. associate--r-73.9%

      \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
    6. metadata-eval73.9%

      \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
    7. +-commutative73.9%

      \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
  3. Simplified73.9%

    \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
  4. Add Preprocessing
  5. Taylor expanded in y around 0 63.7%

    \[\leadsto 1 - \color{blue}{\log \left(1 + -1 \cdot x\right)} \]
  6. Step-by-step derivation
    1. log1p-define63.7%

      \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-1 \cdot x\right)} \]
    2. mul-1-neg63.7%

      \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{-x}\right) \]
  7. Simplified63.7%

    \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-x\right)} \]
  8. Final simplification63.7%

    \[\leadsto 1 - \mathsf{log1p}\left(-x\right) \]
  9. Add Preprocessing

Alternative 9: 40.8% accurate, 37.0× speedup?

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

\\
1 - y
\end{array}
Derivation
  1. Initial program 73.9%

    \[1 - \log \left(1 - \frac{x - y}{1 - y}\right) \]
  2. Step-by-step derivation
    1. sub-neg73.9%

      \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{x - y}{1 - y}\right)\right)} \]
    2. log1p-define73.9%

      \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{x - y}{1 - y}\right)} \]
    3. distribute-neg-frac273.9%

      \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{x - y}{-\left(1 - y\right)}}\right) \]
    4. neg-sub073.9%

      \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{0 - \left(1 - y\right)}}\right) \]
    5. associate--r-73.9%

      \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{\left(0 - 1\right) + y}}\right) \]
    6. metadata-eval73.9%

      \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{-1} + y}\right) \]
    7. +-commutative73.9%

      \[\leadsto 1 - \mathsf{log1p}\left(\frac{x - y}{\color{blue}{y + -1}}\right) \]
  3. Simplified73.9%

    \[\leadsto \color{blue}{1 - \mathsf{log1p}\left(\frac{x - y}{y + -1}\right)} \]
  4. Add Preprocessing
  5. Taylor expanded in x around 0 44.0%

    \[\leadsto 1 - \color{blue}{\log \left(1 - \frac{y}{y - 1}\right)} \]
  6. Step-by-step derivation
    1. sub-neg44.0%

      \[\leadsto 1 - \log \color{blue}{\left(1 + \left(-\frac{y}{y - 1}\right)\right)} \]
    2. mul-1-neg44.0%

      \[\leadsto 1 - \log \left(1 + \color{blue}{-1 \cdot \frac{y}{y - 1}}\right) \]
    3. sub-neg44.0%

      \[\leadsto 1 - \log \left(1 + -1 \cdot \frac{y}{\color{blue}{y + \left(-1\right)}}\right) \]
    4. metadata-eval44.0%

      \[\leadsto 1 - \log \left(1 + -1 \cdot \frac{y}{y + \color{blue}{-1}}\right) \]
    5. neg-mul-144.0%

      \[\leadsto 1 - \log \left(1 + \color{blue}{\left(-\frac{y}{y + -1}\right)}\right) \]
    6. log1p-define44.0%

      \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(-\frac{y}{y + -1}\right)} \]
    7. distribute-neg-frac244.0%

      \[\leadsto 1 - \mathsf{log1p}\left(\color{blue}{\frac{y}{-\left(y + -1\right)}}\right) \]
    8. +-commutative44.0%

      \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{-\color{blue}{\left(-1 + y\right)}}\right) \]
    9. distribute-neg-in44.0%

      \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{\left(--1\right) + \left(-y\right)}}\right) \]
    10. metadata-eval44.0%

      \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{1} + \left(-y\right)}\right) \]
    11. unsub-neg44.0%

      \[\leadsto 1 - \mathsf{log1p}\left(\frac{y}{\color{blue}{1 - y}}\right) \]
  7. Simplified44.0%

    \[\leadsto 1 - \color{blue}{\mathsf{log1p}\left(\frac{y}{1 - y}\right)} \]
  8. Taylor expanded in y around 0 44.0%

    \[\leadsto 1 - \color{blue}{y} \]
  9. Final simplification44.0%

    \[\leadsto 1 - y \]
  10. Add Preprocessing

Developer target: 99.9% accurate, 0.5× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := 1 - \log \left(\frac{x}{y \cdot y} - \left(\frac{1}{y} - \frac{x}{y}\right)\right)\\ \mathbf{if}\;y < -81284752.61947241:\\ \;\;\;\;t\_0\\ \mathbf{elif}\;y < 3.0094271212461764 \cdot 10^{+25}:\\ \;\;\;\;\log \left(\frac{e^{1}}{1 - \frac{x - y}{1 - y}}\right)\\ \mathbf{else}:\\ \;\;\;\;t\_0\\ \end{array} \end{array} \]
(FPCore (x y)
 :precision binary64
 (let* ((t_0 (- 1.0 (log (- (/ x (* y y)) (- (/ 1.0 y) (/ x y)))))))
   (if (< y -81284752.61947241)
     t_0
     (if (< y 3.0094271212461764e+25)
       (log (/ (exp 1.0) (- 1.0 (/ (- x y) (- 1.0 y)))))
       t_0))))
double code(double x, double y) {
	double t_0 = 1.0 - log(((x / (y * y)) - ((1.0 / y) - (x / y))));
	double tmp;
	if (y < -81284752.61947241) {
		tmp = t_0;
	} else if (y < 3.0094271212461764e+25) {
		tmp = log((exp(1.0) / (1.0 - ((x - y) / (1.0 - 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 = 1.0d0 - log(((x / (y * y)) - ((1.0d0 / y) - (x / y))))
    if (y < (-81284752.61947241d0)) then
        tmp = t_0
    else if (y < 3.0094271212461764d+25) then
        tmp = log((exp(1.0d0) / (1.0d0 - ((x - y) / (1.0d0 - y)))))
    else
        tmp = t_0
    end if
    code = tmp
end function
public static double code(double x, double y) {
	double t_0 = 1.0 - Math.log(((x / (y * y)) - ((1.0 / y) - (x / y))));
	double tmp;
	if (y < -81284752.61947241) {
		tmp = t_0;
	} else if (y < 3.0094271212461764e+25) {
		tmp = Math.log((Math.exp(1.0) / (1.0 - ((x - y) / (1.0 - y)))));
	} else {
		tmp = t_0;
	}
	return tmp;
}
def code(x, y):
	t_0 = 1.0 - math.log(((x / (y * y)) - ((1.0 / y) - (x / y))))
	tmp = 0
	if y < -81284752.61947241:
		tmp = t_0
	elif y < 3.0094271212461764e+25:
		tmp = math.log((math.exp(1.0) / (1.0 - ((x - y) / (1.0 - y)))))
	else:
		tmp = t_0
	return tmp
function code(x, y)
	t_0 = Float64(1.0 - log(Float64(Float64(x / Float64(y * y)) - Float64(Float64(1.0 / y) - Float64(x / y)))))
	tmp = 0.0
	if (y < -81284752.61947241)
		tmp = t_0;
	elseif (y < 3.0094271212461764e+25)
		tmp = log(Float64(exp(1.0) / Float64(1.0 - Float64(Float64(x - y) / Float64(1.0 - y)))));
	else
		tmp = t_0;
	end
	return tmp
end
function tmp_2 = code(x, y)
	t_0 = 1.0 - log(((x / (y * y)) - ((1.0 / y) - (x / y))));
	tmp = 0.0;
	if (y < -81284752.61947241)
		tmp = t_0;
	elseif (y < 3.0094271212461764e+25)
		tmp = log((exp(1.0) / (1.0 - ((x - y) / (1.0 - y)))));
	else
		tmp = t_0;
	end
	tmp_2 = tmp;
end
code[x_, y_] := Block[{t$95$0 = N[(1.0 - N[Log[N[(N[(x / N[(y * y), $MachinePrecision]), $MachinePrecision] - N[(N[(1.0 / y), $MachinePrecision] - N[(x / y), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, If[Less[y, -81284752.61947241], t$95$0, If[Less[y, 3.0094271212461764e+25], N[Log[N[(N[Exp[1.0], $MachinePrecision] / N[(1.0 - N[(N[(x - y), $MachinePrecision] / N[(1.0 - y), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision], t$95$0]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := 1 - \log \left(\frac{x}{y \cdot y} - \left(\frac{1}{y} - \frac{x}{y}\right)\right)\\
\mathbf{if}\;y < -81284752.61947241:\\
\;\;\;\;t\_0\\

\mathbf{elif}\;y < 3.0094271212461764 \cdot 10^{+25}:\\
\;\;\;\;\log \left(\frac{e^{1}}{1 - \frac{x - y}{1 - y}}\right)\\

\mathbf{else}:\\
\;\;\;\;t\_0\\


\end{array}
\end{array}

Reproduce

?
herbie shell --seed 2024071 
(FPCore (x y)
  :name "Numeric.SpecFunctions:invIncompleteGamma from math-functions-0.1.5.2, B"
  :precision binary64

  :alt
  (if (< y -81284752.61947241) (- 1.0 (log (- (/ x (* y y)) (- (/ 1.0 y) (/ x y))))) (if (< y 3.0094271212461764e+25) (log (/ (exp 1.0) (- 1.0 (/ (- x y) (- 1.0 y))))) (- 1.0 (log (- (/ x (* y y)) (- (/ 1.0 y) (/ x y)))))))

  (- 1.0 (log (- 1.0 (/ (- x y) (- 1.0 y))))))