Numeric.SpecFunctions.Extra:bd0 from math-functions-0.1.5.2

Percentage Accurate: 76.9% → 99.7%
Time: 7.5s
Alternatives: 5
Speedup: 0.5×

Specification

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

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

Sampling outcomes in binary64 precision:

Local Percentage Accuracy vs ?

The average percentage accuracy by input value. Horizontal axis shows value of an input variable; the variable is choosen in the title. Vertical axis is accuracy; higher is better. Red represent the original program, while blue represents Herbie's suggestion. These can be toggled with buttons below the plot. The line is an average while dots represent individual samples.

Accuracy vs Speed?

Herbie found 5 alternatives:

AlternativeAccuracySpeedup
The accuracy (vertical axis) and speed (horizontal axis) of each alternatives. Up and to the right is better. The red square shows the initial program, and each blue circle shows an alternative.The line shows the best available speed-accuracy tradeoffs.

Initial Program: 76.9% accurate, 1.0× speedup?

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

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

Alternative 1: 99.7% accurate, 0.3× speedup?

\[\begin{array}{l} \\ x \cdot \left(\log \left(\frac{\sqrt[3]{x}}{\sqrt[3]{y}}\right) \cdot 3\right) - z \end{array} \]
(FPCore (x y z)
 :precision binary64
 (- (* x (* (log (/ (cbrt x) (cbrt y))) 3.0)) z))
double code(double x, double y, double z) {
	return (x * (log((cbrt(x) / cbrt(y))) * 3.0)) - z;
}
public static double code(double x, double y, double z) {
	return (x * (Math.log((Math.cbrt(x) / Math.cbrt(y))) * 3.0)) - z;
}
function code(x, y, z)
	return Float64(Float64(x * Float64(log(Float64(cbrt(x) / cbrt(y))) * 3.0)) - z)
end
code[x_, y_, z_] := N[(N[(x * N[(N[Log[N[(N[Power[x, 1/3], $MachinePrecision] / N[Power[y, 1/3], $MachinePrecision]), $MachinePrecision]], $MachinePrecision] * 3.0), $MachinePrecision]), $MachinePrecision] - z), $MachinePrecision]
\begin{array}{l}

\\
x \cdot \left(\log \left(\frac{\sqrt[3]{x}}{\sqrt[3]{y}}\right) \cdot 3\right) - z
\end{array}
Derivation
  1. Initial program 82.5%

    \[x \cdot \log \left(\frac{x}{y}\right) - z \]
  2. Step-by-step derivation
    1. add-cube-cbrt82.5%

      \[\leadsto x \cdot \log \color{blue}{\left(\left(\sqrt[3]{\frac{x}{y}} \cdot \sqrt[3]{\frac{x}{y}}\right) \cdot \sqrt[3]{\frac{x}{y}}\right)} - z \]
    2. associate-*l*82.5%

      \[\leadsto x \cdot \log \color{blue}{\left(\sqrt[3]{\frac{x}{y}} \cdot \left(\sqrt[3]{\frac{x}{y}} \cdot \sqrt[3]{\frac{x}{y}}\right)\right)} - z \]
    3. log-prod82.5%

      \[\leadsto x \cdot \color{blue}{\left(\log \left(\sqrt[3]{\frac{x}{y}}\right) + \log \left(\sqrt[3]{\frac{x}{y}} \cdot \sqrt[3]{\frac{x}{y}}\right)\right)} - z \]
    4. pow282.5%

      \[\leadsto x \cdot \left(\log \left(\sqrt[3]{\frac{x}{y}}\right) + \log \color{blue}{\left({\left(\sqrt[3]{\frac{x}{y}}\right)}^{2}\right)}\right) - z \]
    5. metadata-eval82.5%

      \[\leadsto x \cdot \left(\log \left(\sqrt[3]{\frac{x}{y}}\right) + \log \left({\left(\sqrt[3]{\frac{x}{y}}\right)}^{\color{blue}{\left(1 + 1\right)}}\right)\right) - z \]
    6. log-pow82.5%

      \[\leadsto x \cdot \left(\log \left(\sqrt[3]{\frac{x}{y}}\right) + \color{blue}{\left(1 + 1\right) \cdot \log \left(\sqrt[3]{\frac{x}{y}}\right)}\right) - z \]
    7. metadata-eval82.5%

      \[\leadsto x \cdot \left(\log \left(\sqrt[3]{\frac{x}{y}}\right) + \color{blue}{2} \cdot \log \left(\sqrt[3]{\frac{x}{y}}\right)\right) - z \]
  3. Applied egg-rr82.5%

    \[\leadsto x \cdot \color{blue}{\left(\log \left(\sqrt[3]{\frac{x}{y}}\right) + 2 \cdot \log \left(\sqrt[3]{\frac{x}{y}}\right)\right)} - z \]
  4. Step-by-step derivation
    1. distribute-rgt1-in82.5%

      \[\leadsto x \cdot \color{blue}{\left(\left(2 + 1\right) \cdot \log \left(\sqrt[3]{\frac{x}{y}}\right)\right)} - z \]
    2. metadata-eval82.5%

      \[\leadsto x \cdot \left(\color{blue}{3} \cdot \log \left(\sqrt[3]{\frac{x}{y}}\right)\right) - z \]
    3. *-commutative82.5%

      \[\leadsto x \cdot \color{blue}{\left(\log \left(\sqrt[3]{\frac{x}{y}}\right) \cdot 3\right)} - z \]
  5. Simplified82.5%

    \[\leadsto x \cdot \color{blue}{\left(\log \left(\sqrt[3]{\frac{x}{y}}\right) \cdot 3\right)} - z \]
  6. Step-by-step derivation
    1. cbrt-div99.8%

      \[\leadsto x \cdot \left(\log \color{blue}{\left(\frac{\sqrt[3]{x}}{\sqrt[3]{y}}\right)} \cdot 3\right) - z \]
    2. div-inv99.8%

      \[\leadsto x \cdot \left(\log \color{blue}{\left(\sqrt[3]{x} \cdot \frac{1}{\sqrt[3]{y}}\right)} \cdot 3\right) - z \]
  7. Applied egg-rr99.8%

    \[\leadsto x \cdot \left(\log \color{blue}{\left(\sqrt[3]{x} \cdot \frac{1}{\sqrt[3]{y}}\right)} \cdot 3\right) - z \]
  8. Step-by-step derivation
    1. associate-*r/99.8%

      \[\leadsto x \cdot \left(\log \color{blue}{\left(\frac{\sqrt[3]{x} \cdot 1}{\sqrt[3]{y}}\right)} \cdot 3\right) - z \]
    2. *-rgt-identity99.8%

      \[\leadsto x \cdot \left(\log \left(\frac{\color{blue}{\sqrt[3]{x}}}{\sqrt[3]{y}}\right) \cdot 3\right) - z \]
  9. Simplified99.8%

    \[\leadsto x \cdot \left(\log \color{blue}{\left(\frac{\sqrt[3]{x}}{\sqrt[3]{y}}\right)} \cdot 3\right) - z \]
  10. Final simplification99.8%

    \[\leadsto x \cdot \left(\log \left(\frac{\sqrt[3]{x}}{\sqrt[3]{y}}\right) \cdot 3\right) - z \]

Alternative 2: 86.5% accurate, 0.3× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := x \cdot \log \left(\frac{x}{y}\right)\\ \mathbf{if}\;t_0 \leq -\infty:\\ \;\;\;\;-z\\ \mathbf{elif}\;t_0 \leq 2 \cdot 10^{+294}:\\ \;\;\;\;t_0 - z\\ \mathbf{else}:\\ \;\;\;\;-z\\ \end{array} \end{array} \]
(FPCore (x y z)
 :precision binary64
 (let* ((t_0 (* x (log (/ x y)))))
   (if (<= t_0 (- INFINITY)) (- z) (if (<= t_0 2e+294) (- t_0 z) (- z)))))
double code(double x, double y, double z) {
	double t_0 = x * log((x / y));
	double tmp;
	if (t_0 <= -((double) INFINITY)) {
		tmp = -z;
	} else if (t_0 <= 2e+294) {
		tmp = t_0 - z;
	} else {
		tmp = -z;
	}
	return tmp;
}
public static double code(double x, double y, double z) {
	double t_0 = x * Math.log((x / y));
	double tmp;
	if (t_0 <= -Double.POSITIVE_INFINITY) {
		tmp = -z;
	} else if (t_0 <= 2e+294) {
		tmp = t_0 - z;
	} else {
		tmp = -z;
	}
	return tmp;
}
def code(x, y, z):
	t_0 = x * math.log((x / y))
	tmp = 0
	if t_0 <= -math.inf:
		tmp = -z
	elif t_0 <= 2e+294:
		tmp = t_0 - z
	else:
		tmp = -z
	return tmp
function code(x, y, z)
	t_0 = Float64(x * log(Float64(x / y)))
	tmp = 0.0
	if (t_0 <= Float64(-Inf))
		tmp = Float64(-z);
	elseif (t_0 <= 2e+294)
		tmp = Float64(t_0 - z);
	else
		tmp = Float64(-z);
	end
	return tmp
end
function tmp_2 = code(x, y, z)
	t_0 = x * log((x / y));
	tmp = 0.0;
	if (t_0 <= -Inf)
		tmp = -z;
	elseif (t_0 <= 2e+294)
		tmp = t_0 - z;
	else
		tmp = -z;
	end
	tmp_2 = tmp;
end
code[x_, y_, z_] := Block[{t$95$0 = N[(x * N[Log[N[(x / y), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, If[LessEqual[t$95$0, (-Infinity)], (-z), If[LessEqual[t$95$0, 2e+294], N[(t$95$0 - z), $MachinePrecision], (-z)]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := x \cdot \log \left(\frac{x}{y}\right)\\
\mathbf{if}\;t_0 \leq -\infty:\\
\;\;\;\;-z\\

\mathbf{elif}\;t_0 \leq 2 \cdot 10^{+294}:\\
\;\;\;\;t_0 - z\\

\mathbf{else}:\\
\;\;\;\;-z\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (*.f64 x (log.f64 (/.f64 x y))) < -inf.0 or 2.00000000000000013e294 < (*.f64 x (log.f64 (/.f64 x y)))

    1. Initial program 3.4%

      \[x \cdot \log \left(\frac{x}{y}\right) - z \]
    2. Taylor expanded in x around 0 62.1%

      \[\leadsto \color{blue}{-1 \cdot z} \]
    3. Step-by-step derivation
      1. neg-mul-162.1%

        \[\leadsto \color{blue}{-z} \]
    4. Simplified62.1%

      \[\leadsto \color{blue}{-z} \]

    if -inf.0 < (*.f64 x (log.f64 (/.f64 x y))) < 2.00000000000000013e294

    1. Initial program 99.9%

      \[x \cdot \log \left(\frac{x}{y}\right) - z \]
  3. Recombined 2 regimes into one program.
  4. Final simplification93.1%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \cdot \log \left(\frac{x}{y}\right) \leq -\infty:\\ \;\;\;\;-z\\ \mathbf{elif}\;x \cdot \log \left(\frac{x}{y}\right) \leq 2 \cdot 10^{+294}:\\ \;\;\;\;x \cdot \log \left(\frac{x}{y}\right) - z\\ \mathbf{else}:\\ \;\;\;\;-z\\ \end{array} \]

Alternative 3: 91.1% accurate, 0.5× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq -6 \cdot 10^{-153}:\\ \;\;\;\;x \cdot \log \left(\frac{x}{y}\right) - z\\ \mathbf{elif}\;x \leq -2 \cdot 10^{-310}:\\ \;\;\;\;-z\\ \mathbf{else}:\\ \;\;\;\;x \cdot \left(\log x - \log y\right) - z\\ \end{array} \end{array} \]
(FPCore (x y z)
 :precision binary64
 (if (<= x -6e-153)
   (- (* x (log (/ x y))) z)
   (if (<= x -2e-310) (- z) (- (* x (- (log x) (log y))) z))))
double code(double x, double y, double z) {
	double tmp;
	if (x <= -6e-153) {
		tmp = (x * log((x / y))) - z;
	} else if (x <= -2e-310) {
		tmp = -z;
	} else {
		tmp = (x * (log(x) - log(y))) - z;
	}
	return tmp;
}
real(8) function code(x, y, z)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    real(8) :: tmp
    if (x <= (-6d-153)) then
        tmp = (x * log((x / y))) - z
    else if (x <= (-2d-310)) then
        tmp = -z
    else
        tmp = (x * (log(x) - log(y))) - z
    end if
    code = tmp
end function
public static double code(double x, double y, double z) {
	double tmp;
	if (x <= -6e-153) {
		tmp = (x * Math.log((x / y))) - z;
	} else if (x <= -2e-310) {
		tmp = -z;
	} else {
		tmp = (x * (Math.log(x) - Math.log(y))) - z;
	}
	return tmp;
}
def code(x, y, z):
	tmp = 0
	if x <= -6e-153:
		tmp = (x * math.log((x / y))) - z
	elif x <= -2e-310:
		tmp = -z
	else:
		tmp = (x * (math.log(x) - math.log(y))) - z
	return tmp
function code(x, y, z)
	tmp = 0.0
	if (x <= -6e-153)
		tmp = Float64(Float64(x * log(Float64(x / y))) - z);
	elseif (x <= -2e-310)
		tmp = Float64(-z);
	else
		tmp = Float64(Float64(x * Float64(log(x) - log(y))) - z);
	end
	return tmp
end
function tmp_2 = code(x, y, z)
	tmp = 0.0;
	if (x <= -6e-153)
		tmp = (x * log((x / y))) - z;
	elseif (x <= -2e-310)
		tmp = -z;
	else
		tmp = (x * (log(x) - log(y))) - z;
	end
	tmp_2 = tmp;
end
code[x_, y_, z_] := If[LessEqual[x, -6e-153], N[(N[(x * N[Log[N[(x / y), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] - z), $MachinePrecision], If[LessEqual[x, -2e-310], (-z), N[(N[(x * N[(N[Log[x], $MachinePrecision] - N[Log[y], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] - z), $MachinePrecision]]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq -6 \cdot 10^{-153}:\\
\;\;\;\;x \cdot \log \left(\frac{x}{y}\right) - z\\

\mathbf{elif}\;x \leq -2 \cdot 10^{-310}:\\
\;\;\;\;-z\\

\mathbf{else}:\\
\;\;\;\;x \cdot \left(\log x - \log y\right) - z\\


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if x < -6e-153

    1. Initial program 87.7%

      \[x \cdot \log \left(\frac{x}{y}\right) - z \]

    if -6e-153 < x < -1.999999999999994e-310

    1. Initial program 66.4%

      \[x \cdot \log \left(\frac{x}{y}\right) - z \]
    2. Taylor expanded in x around 0 85.1%

      \[\leadsto \color{blue}{-1 \cdot z} \]
    3. Step-by-step derivation
      1. neg-mul-185.1%

        \[\leadsto \color{blue}{-z} \]
    4. Simplified85.1%

      \[\leadsto \color{blue}{-z} \]

    if -1.999999999999994e-310 < x

    1. Initial program 83.6%

      \[x \cdot \log \left(\frac{x}{y}\right) - z \]
    2. Step-by-step derivation
      1. log-div99.7%

        \[\leadsto x \cdot \color{blue}{\left(\log x - \log y\right)} - z \]
    3. Applied egg-rr99.7%

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

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -6 \cdot 10^{-153}:\\ \;\;\;\;x \cdot \log \left(\frac{x}{y}\right) - z\\ \mathbf{elif}\;x \leq -2 \cdot 10^{-310}:\\ \;\;\;\;-z\\ \mathbf{else}:\\ \;\;\;\;x \cdot \left(\log x - \log y\right) - z\\ \end{array} \]

Alternative 4: 99.5% accurate, 0.5× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;y \leq -5 \cdot 10^{-310}:\\ \;\;\;\;x \cdot \left(\log \left(-x\right) - \log \left(-y\right)\right) - z\\ \mathbf{else}:\\ \;\;\;\;x \cdot \left(\log x - \log y\right) - z\\ \end{array} \end{array} \]
(FPCore (x y z)
 :precision binary64
 (if (<= y -5e-310)
   (- (* x (- (log (- x)) (log (- y)))) z)
   (- (* x (- (log x) (log y))) z)))
double code(double x, double y, double z) {
	double tmp;
	if (y <= -5e-310) {
		tmp = (x * (log(-x) - log(-y))) - z;
	} else {
		tmp = (x * (log(x) - log(y))) - z;
	}
	return tmp;
}
real(8) function code(x, y, z)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    real(8) :: tmp
    if (y <= (-5d-310)) then
        tmp = (x * (log(-x) - log(-y))) - z
    else
        tmp = (x * (log(x) - log(y))) - z
    end if
    code = tmp
end function
public static double code(double x, double y, double z) {
	double tmp;
	if (y <= -5e-310) {
		tmp = (x * (Math.log(-x) - Math.log(-y))) - z;
	} else {
		tmp = (x * (Math.log(x) - Math.log(y))) - z;
	}
	return tmp;
}
def code(x, y, z):
	tmp = 0
	if y <= -5e-310:
		tmp = (x * (math.log(-x) - math.log(-y))) - z
	else:
		tmp = (x * (math.log(x) - math.log(y))) - z
	return tmp
function code(x, y, z)
	tmp = 0.0
	if (y <= -5e-310)
		tmp = Float64(Float64(x * Float64(log(Float64(-x)) - log(Float64(-y)))) - z);
	else
		tmp = Float64(Float64(x * Float64(log(x) - log(y))) - z);
	end
	return tmp
end
function tmp_2 = code(x, y, z)
	tmp = 0.0;
	if (y <= -5e-310)
		tmp = (x * (log(-x) - log(-y))) - z;
	else
		tmp = (x * (log(x) - log(y))) - z;
	end
	tmp_2 = tmp;
end
code[x_, y_, z_] := If[LessEqual[y, -5e-310], N[(N[(x * N[(N[Log[(-x)], $MachinePrecision] - N[Log[(-y)], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] - z), $MachinePrecision], N[(N[(x * N[(N[Log[x], $MachinePrecision] - N[Log[y], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] - z), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;y \leq -5 \cdot 10^{-310}:\\
\;\;\;\;x \cdot \left(\log \left(-x\right) - \log \left(-y\right)\right) - z\\

\mathbf{else}:\\
\;\;\;\;x \cdot \left(\log x - \log y\right) - z\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if y < -4.999999999999985e-310

    1. Initial program 81.5%

      \[x \cdot \log \left(\frac{x}{y}\right) - z \]
    2. Step-by-step derivation
      1. frac-2neg81.5%

        \[\leadsto x \cdot \log \color{blue}{\left(\frac{-x}{-y}\right)} - z \]
      2. log-div99.4%

        \[\leadsto x \cdot \color{blue}{\left(\log \left(-x\right) - \log \left(-y\right)\right)} - z \]
    3. Applied egg-rr99.4%

      \[\leadsto x \cdot \color{blue}{\left(\log \left(-x\right) - \log \left(-y\right)\right)} - z \]

    if -4.999999999999985e-310 < y

    1. Initial program 83.6%

      \[x \cdot \log \left(\frac{x}{y}\right) - z \]
    2. Step-by-step derivation
      1. log-div99.7%

        \[\leadsto x \cdot \color{blue}{\left(\log x - \log y\right)} - z \]
    3. Applied egg-rr99.7%

      \[\leadsto x \cdot \color{blue}{\left(\log x - \log y\right)} - z \]
  3. Recombined 2 regimes into one program.
  4. Final simplification99.5%

    \[\leadsto \begin{array}{l} \mathbf{if}\;y \leq -5 \cdot 10^{-310}:\\ \;\;\;\;x \cdot \left(\log \left(-x\right) - \log \left(-y\right)\right) - z\\ \mathbf{else}:\\ \;\;\;\;x \cdot \left(\log x - \log y\right) - z\\ \end{array} \]

Alternative 5: 50.6% accurate, 53.5× speedup?

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

\\
-z
\end{array}
Derivation
  1. Initial program 82.5%

    \[x \cdot \log \left(\frac{x}{y}\right) - z \]
  2. Taylor expanded in x around 0 55.8%

    \[\leadsto \color{blue}{-1 \cdot z} \]
  3. Step-by-step derivation
    1. neg-mul-155.8%

      \[\leadsto \color{blue}{-z} \]
  4. Simplified55.8%

    \[\leadsto \color{blue}{-z} \]
  5. Final simplification55.8%

    \[\leadsto -z \]

Developer target: 88.6% accurate, 0.5× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;y < 7.595077799083773 \cdot 10^{-308}:\\ \;\;\;\;x \cdot \log \left(\frac{x}{y}\right) - z\\ \mathbf{else}:\\ \;\;\;\;x \cdot \left(\log x - \log y\right) - z\\ \end{array} \end{array} \]
(FPCore (x y z)
 :precision binary64
 (if (< y 7.595077799083773e-308)
   (- (* x (log (/ x y))) z)
   (- (* x (- (log x) (log y))) z)))
double code(double x, double y, double z) {
	double tmp;
	if (y < 7.595077799083773e-308) {
		tmp = (x * log((x / y))) - z;
	} else {
		tmp = (x * (log(x) - log(y))) - z;
	}
	return tmp;
}
real(8) function code(x, y, z)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    real(8) :: tmp
    if (y < 7.595077799083773d-308) then
        tmp = (x * log((x / y))) - z
    else
        tmp = (x * (log(x) - log(y))) - z
    end if
    code = tmp
end function
public static double code(double x, double y, double z) {
	double tmp;
	if (y < 7.595077799083773e-308) {
		tmp = (x * Math.log((x / y))) - z;
	} else {
		tmp = (x * (Math.log(x) - Math.log(y))) - z;
	}
	return tmp;
}
def code(x, y, z):
	tmp = 0
	if y < 7.595077799083773e-308:
		tmp = (x * math.log((x / y))) - z
	else:
		tmp = (x * (math.log(x) - math.log(y))) - z
	return tmp
function code(x, y, z)
	tmp = 0.0
	if (y < 7.595077799083773e-308)
		tmp = Float64(Float64(x * log(Float64(x / y))) - z);
	else
		tmp = Float64(Float64(x * Float64(log(x) - log(y))) - z);
	end
	return tmp
end
function tmp_2 = code(x, y, z)
	tmp = 0.0;
	if (y < 7.595077799083773e-308)
		tmp = (x * log((x / y))) - z;
	else
		tmp = (x * (log(x) - log(y))) - z;
	end
	tmp_2 = tmp;
end
code[x_, y_, z_] := If[Less[y, 7.595077799083773e-308], N[(N[(x * N[Log[N[(x / y), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] - z), $MachinePrecision], N[(N[(x * N[(N[Log[x], $MachinePrecision] - N[Log[y], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] - z), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;y < 7.595077799083773 \cdot 10^{-308}:\\
\;\;\;\;x \cdot \log \left(\frac{x}{y}\right) - z\\

\mathbf{else}:\\
\;\;\;\;x \cdot \left(\log x - \log y\right) - z\\


\end{array}
\end{array}

Reproduce

?
herbie shell --seed 2023293 
(FPCore (x y z)
  :name "Numeric.SpecFunctions.Extra:bd0 from math-functions-0.1.5.2"
  :precision binary64

  :herbie-target
  (if (< y 7.595077799083773e-308) (- (* x (log (/ x y))) z) (- (* x (- (log x) (log y))) z))

  (- (* x (log (/ x y))) z))