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

Percentage Accurate: 77.3% → 99.5%
Time: 6.3s
Alternatives: 6
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;
}
module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(8) function code(x, y, z)
use fmin_fmax_functions
    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 6 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: 77.3% 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;
}
module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(8) function code(x, y, z)
use fmin_fmax_functions
    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: 99.5% accurate, 0.5× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;y \leq -2 \cdot 10^{-310}:\\ \;\;\;\;x \cdot \left(\log \left(-x\right) - \log \left(-y\right)\right) - z\\ \mathbf{else}:\\ \;\;\;\;\mathsf{fma}\left(\log x - \log y, x, -z\right)\\ \end{array} \end{array} \]
(FPCore (x y z)
 :precision binary64
 (if (<= y -2e-310)
   (- (* x (- (log (- x)) (log (- y)))) z)
   (fma (- (log x) (log y)) x (- z))))
double code(double x, double y, double z) {
	double tmp;
	if (y <= -2e-310) {
		tmp = (x * (log(-x) - log(-y))) - z;
	} else {
		tmp = fma((log(x) - log(y)), x, -z);
	}
	return tmp;
}
function code(x, y, z)
	tmp = 0.0
	if (y <= -2e-310)
		tmp = Float64(Float64(x * Float64(log(Float64(-x)) - log(Float64(-y)))) - z);
	else
		tmp = fma(Float64(log(x) - log(y)), x, Float64(-z));
	end
	return tmp
end
code[x_, y_, z_] := If[LessEqual[y, -2e-310], N[(N[(x * N[(N[Log[(-x)], $MachinePrecision] - N[Log[(-y)], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] - z), $MachinePrecision], N[(N[(N[Log[x], $MachinePrecision] - N[Log[y], $MachinePrecision]), $MachinePrecision] * x + (-z)), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;y \leq -2 \cdot 10^{-310}:\\
\;\;\;\;x \cdot \left(\log \left(-x\right) - \log \left(-y\right)\right) - z\\

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


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if y < -1.999999999999994e-310

    1. Initial program 80.5%

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

        \[\leadsto x \cdot \color{blue}{\log \left(\frac{x}{y}\right)} - z \]
      2. lift-/.f64N/A

        \[\leadsto x \cdot \log \color{blue}{\left(\frac{x}{y}\right)} - z \]
      3. frac-2negN/A

        \[\leadsto x \cdot \log \color{blue}{\left(\frac{\mathsf{neg}\left(x\right)}{\mathsf{neg}\left(y\right)}\right)} - z \]
      4. log-divN/A

        \[\leadsto x \cdot \color{blue}{\left(\log \left(\mathsf{neg}\left(x\right)\right) - \log \left(\mathsf{neg}\left(y\right)\right)\right)} - z \]
      5. lower--.f64N/A

        \[\leadsto x \cdot \color{blue}{\left(\log \left(\mathsf{neg}\left(x\right)\right) - \log \left(\mathsf{neg}\left(y\right)\right)\right)} - z \]
      6. lower-log.f64N/A

        \[\leadsto x \cdot \left(\color{blue}{\log \left(\mathsf{neg}\left(x\right)\right)} - \log \left(\mathsf{neg}\left(y\right)\right)\right) - z \]
      7. lower-neg.f64N/A

        \[\leadsto x \cdot \left(\log \color{blue}{\left(-x\right)} - \log \left(\mathsf{neg}\left(y\right)\right)\right) - z \]
      8. lower-log.f64N/A

        \[\leadsto x \cdot \left(\log \left(-x\right) - \color{blue}{\log \left(\mathsf{neg}\left(y\right)\right)}\right) - z \]
      9. lower-neg.f6499.4

        \[\leadsto x \cdot \left(\log \left(-x\right) - \log \color{blue}{\left(-y\right)}\right) - z \]
    4. Applied rewrites99.4%

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

    if -1.999999999999994e-310 < y

    1. Initial program 77.8%

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

      \[\leadsto \color{blue}{x \cdot \left(\log x + \log \left(\frac{1}{y}\right)\right) - z} \]
    4. Applied rewrites99.5%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\log x - \log y, x, -z\right)} \]
  3. Recombined 2 regimes into one program.
  4. Add Preprocessing

Alternative 2: 87.6% accurate, 0.3× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := x \cdot \log \left(\frac{x}{y}\right) - z\\ \mathbf{if}\;t\_0 \leq -\infty \lor \neg \left(t\_0 \leq 4 \cdot 10^{+304}\right):\\ \;\;\;\;-z\\ \mathbf{else}:\\ \;\;\;\;t\_0\\ \end{array} \end{array} \]
(FPCore (x y z)
 :precision binary64
 (let* ((t_0 (- (* x (log (/ x y))) z)))
   (if (or (<= t_0 (- INFINITY)) (not (<= t_0 4e+304))) (- z) t_0)))
double code(double x, double y, double z) {
	double t_0 = (x * log((x / y))) - z;
	double tmp;
	if ((t_0 <= -((double) INFINITY)) || !(t_0 <= 4e+304)) {
		tmp = -z;
	} else {
		tmp = t_0;
	}
	return tmp;
}
public static double code(double x, double y, double z) {
	double t_0 = (x * Math.log((x / y))) - z;
	double tmp;
	if ((t_0 <= -Double.POSITIVE_INFINITY) || !(t_0 <= 4e+304)) {
		tmp = -z;
	} else {
		tmp = t_0;
	}
	return tmp;
}
def code(x, y, z):
	t_0 = (x * math.log((x / y))) - z
	tmp = 0
	if (t_0 <= -math.inf) or not (t_0 <= 4e+304):
		tmp = -z
	else:
		tmp = t_0
	return tmp
function code(x, y, z)
	t_0 = Float64(Float64(x * log(Float64(x / y))) - z)
	tmp = 0.0
	if ((t_0 <= Float64(-Inf)) || !(t_0 <= 4e+304))
		tmp = Float64(-z);
	else
		tmp = t_0;
	end
	return tmp
end
function tmp_2 = code(x, y, z)
	t_0 = (x * log((x / y))) - z;
	tmp = 0.0;
	if ((t_0 <= -Inf) || ~((t_0 <= 4e+304)))
		tmp = -z;
	else
		tmp = t_0;
	end
	tmp_2 = tmp;
end
code[x_, y_, z_] := Block[{t$95$0 = N[(N[(x * N[Log[N[(x / y), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] - z), $MachinePrecision]}, If[Or[LessEqual[t$95$0, (-Infinity)], N[Not[LessEqual[t$95$0, 4e+304]], $MachinePrecision]], (-z), t$95$0]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := x \cdot \log \left(\frac{x}{y}\right) - z\\
\mathbf{if}\;t\_0 \leq -\infty \lor \neg \left(t\_0 \leq 4 \cdot 10^{+304}\right):\\
\;\;\;\;-z\\

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


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (-.f64 (*.f64 x (log.f64 (/.f64 x y))) z) < -inf.0 or 3.9999999999999998e304 < (-.f64 (*.f64 x (log.f64 (/.f64 x y))) z)

    1. Initial program 4.6%

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

      \[\leadsto \color{blue}{-1 \cdot z} \]
    4. Step-by-step derivation
      1. mul-1-negN/A

        \[\leadsto \color{blue}{\mathsf{neg}\left(z\right)} \]
      2. lower-neg.f6452.3

        \[\leadsto \color{blue}{-z} \]
    5. Applied rewrites52.3%

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

    if -inf.0 < (-.f64 (*.f64 x (log.f64 (/.f64 x y))) z) < 3.9999999999999998e304

    1. Initial program 99.6%

      \[x \cdot \log \left(\frac{x}{y}\right) - z \]
    2. Add Preprocessing
  3. Recombined 2 regimes into one program.
  4. Final simplification89.4%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \cdot \log \left(\frac{x}{y}\right) - z \leq -\infty \lor \neg \left(x \cdot \log \left(\frac{x}{y}\right) - z \leq 4 \cdot 10^{+304}\right):\\ \;\;\;\;-z\\ \mathbf{else}:\\ \;\;\;\;x \cdot \log \left(\frac{x}{y}\right) - z\\ \end{array} \]
  5. Add Preprocessing

Alternative 3: 92.9% accurate, 0.5× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq -6.5 \cdot 10^{+120}:\\ \;\;\;\;\left(\log \left(-x\right) - \log \left(-y\right)\right) \cdot x\\ \mathbf{elif}\;x \leq -9.8 \cdot 10^{-176}:\\ \;\;\;\;x \cdot \log \left(\frac{x}{y}\right) - z\\ \mathbf{elif}\;x \leq -5 \cdot 10^{-308}:\\ \;\;\;\;-z\\ \mathbf{else}:\\ \;\;\;\;\mathsf{fma}\left(\log x - \log y, x, -z\right)\\ \end{array} \end{array} \]
(FPCore (x y z)
 :precision binary64
 (if (<= x -6.5e+120)
   (* (- (log (- x)) (log (- y))) x)
   (if (<= x -9.8e-176)
     (- (* x (log (/ x y))) z)
     (if (<= x -5e-308) (- z) (fma (- (log x) (log y)) x (- z))))))
double code(double x, double y, double z) {
	double tmp;
	if (x <= -6.5e+120) {
		tmp = (log(-x) - log(-y)) * x;
	} else if (x <= -9.8e-176) {
		tmp = (x * log((x / y))) - z;
	} else if (x <= -5e-308) {
		tmp = -z;
	} else {
		tmp = fma((log(x) - log(y)), x, -z);
	}
	return tmp;
}
function code(x, y, z)
	tmp = 0.0
	if (x <= -6.5e+120)
		tmp = Float64(Float64(log(Float64(-x)) - log(Float64(-y))) * x);
	elseif (x <= -9.8e-176)
		tmp = Float64(Float64(x * log(Float64(x / y))) - z);
	elseif (x <= -5e-308)
		tmp = Float64(-z);
	else
		tmp = fma(Float64(log(x) - log(y)), x, Float64(-z));
	end
	return tmp
end
code[x_, y_, z_] := If[LessEqual[x, -6.5e+120], N[(N[(N[Log[(-x)], $MachinePrecision] - N[Log[(-y)], $MachinePrecision]), $MachinePrecision] * x), $MachinePrecision], If[LessEqual[x, -9.8e-176], N[(N[(x * N[Log[N[(x / y), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] - z), $MachinePrecision], If[LessEqual[x, -5e-308], (-z), N[(N[(N[Log[x], $MachinePrecision] - N[Log[y], $MachinePrecision]), $MachinePrecision] * x + (-z)), $MachinePrecision]]]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq -6.5 \cdot 10^{+120}:\\
\;\;\;\;\left(\log \left(-x\right) - \log \left(-y\right)\right) \cdot x\\

\mathbf{elif}\;x \leq -9.8 \cdot 10^{-176}:\\
\;\;\;\;x \cdot \log \left(\frac{x}{y}\right) - z\\

\mathbf{elif}\;x \leq -5 \cdot 10^{-308}:\\
\;\;\;\;-z\\

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


\end{array}
\end{array}
Derivation
  1. Split input into 4 regimes
  2. if x < -6.4999999999999997e120

    1. Initial program 74.1%

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

      \[\leadsto \color{blue}{x \cdot \log \left(\frac{x}{y}\right)} \]
    4. Step-by-step derivation
      1. *-commutativeN/A

        \[\leadsto \color{blue}{\log \left(\frac{x}{y}\right) \cdot x} \]
      2. lower-*.f64N/A

        \[\leadsto \color{blue}{\log \left(\frac{x}{y}\right) \cdot x} \]
      3. lower-log.f64N/A

        \[\leadsto \color{blue}{\log \left(\frac{x}{y}\right)} \cdot x \]
      4. lower-/.f6471.4

        \[\leadsto \log \color{blue}{\left(\frac{x}{y}\right)} \cdot x \]
    5. Applied rewrites71.4%

      \[\leadsto \color{blue}{\log \left(\frac{x}{y}\right) \cdot x} \]
    6. Step-by-step derivation
      1. Applied rewrites90.3%

        \[\leadsto \left(\log \left(-x\right) - \log \left(-y\right)\right) \cdot x \]

      if -6.4999999999999997e120 < x < -9.7999999999999994e-176

      1. Initial program 89.5%

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

      if -9.7999999999999994e-176 < x < -4.99999999999999955e-308

      1. Initial program 67.0%

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

        \[\leadsto \color{blue}{-1 \cdot z} \]
      4. Step-by-step derivation
        1. mul-1-negN/A

          \[\leadsto \color{blue}{\mathsf{neg}\left(z\right)} \]
        2. lower-neg.f6489.5

          \[\leadsto \color{blue}{-z} \]
      5. Applied rewrites89.5%

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

      if -4.99999999999999955e-308 < x

      1. Initial program 77.8%

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

        \[\leadsto \color{blue}{x \cdot \left(\log x + \log \left(\frac{1}{y}\right)\right) - z} \]
      4. Applied rewrites99.5%

        \[\leadsto \color{blue}{\mathsf{fma}\left(\log x - \log y, x, -z\right)} \]
    7. Recombined 4 regimes into one program.
    8. Add Preprocessing

    Alternative 4: 90.8% accurate, 0.5× speedup?

    \[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq -9.8 \cdot 10^{-176}:\\ \;\;\;\;x \cdot \log \left(\frac{x}{y}\right) - z\\ \mathbf{elif}\;x \leq -5 \cdot 10^{-308}:\\ \;\;\;\;-z\\ \mathbf{else}:\\ \;\;\;\;\mathsf{fma}\left(\log x - \log y, x, -z\right)\\ \end{array} \end{array} \]
    (FPCore (x y z)
     :precision binary64
     (if (<= x -9.8e-176)
       (- (* x (log (/ x y))) z)
       (if (<= x -5e-308) (- z) (fma (- (log x) (log y)) x (- z)))))
    double code(double x, double y, double z) {
    	double tmp;
    	if (x <= -9.8e-176) {
    		tmp = (x * log((x / y))) - z;
    	} else if (x <= -5e-308) {
    		tmp = -z;
    	} else {
    		tmp = fma((log(x) - log(y)), x, -z);
    	}
    	return tmp;
    }
    
    function code(x, y, z)
    	tmp = 0.0
    	if (x <= -9.8e-176)
    		tmp = Float64(Float64(x * log(Float64(x / y))) - z);
    	elseif (x <= -5e-308)
    		tmp = Float64(-z);
    	else
    		tmp = fma(Float64(log(x) - log(y)), x, Float64(-z));
    	end
    	return tmp
    end
    
    code[x_, y_, z_] := If[LessEqual[x, -9.8e-176], N[(N[(x * N[Log[N[(x / y), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] - z), $MachinePrecision], If[LessEqual[x, -5e-308], (-z), N[(N[(N[Log[x], $MachinePrecision] - N[Log[y], $MachinePrecision]), $MachinePrecision] * x + (-z)), $MachinePrecision]]]
    
    \begin{array}{l}
    
    \\
    \begin{array}{l}
    \mathbf{if}\;x \leq -9.8 \cdot 10^{-176}:\\
    \;\;\;\;x \cdot \log \left(\frac{x}{y}\right) - z\\
    
    \mathbf{elif}\;x \leq -5 \cdot 10^{-308}:\\
    \;\;\;\;-z\\
    
    \mathbf{else}:\\
    \;\;\;\;\mathsf{fma}\left(\log x - \log y, x, -z\right)\\
    
    
    \end{array}
    \end{array}
    
    Derivation
    1. Split input into 3 regimes
    2. if x < -9.7999999999999994e-176

      1. Initial program 84.0%

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

      if -9.7999999999999994e-176 < x < -4.99999999999999955e-308

      1. Initial program 67.0%

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

        \[\leadsto \color{blue}{-1 \cdot z} \]
      4. Step-by-step derivation
        1. mul-1-negN/A

          \[\leadsto \color{blue}{\mathsf{neg}\left(z\right)} \]
        2. lower-neg.f6489.5

          \[\leadsto \color{blue}{-z} \]
      5. Applied rewrites89.5%

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

      if -4.99999999999999955e-308 < x

      1. Initial program 77.8%

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

        \[\leadsto \color{blue}{x \cdot \left(\log x + \log \left(\frac{1}{y}\right)\right) - z} \]
      4. Applied rewrites99.5%

        \[\leadsto \color{blue}{\mathsf{fma}\left(\log x - \log y, x, -z\right)} \]
    3. Recombined 3 regimes into one program.
    4. Add Preprocessing

    Alternative 5: 68.0% accurate, 0.9× speedup?

    \[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;z \leq -0.38 \lor \neg \left(z \leq 1700000000\right):\\ \;\;\;\;-z\\ \mathbf{else}:\\ \;\;\;\;\log \left(\frac{x}{y}\right) \cdot x\\ \end{array} \end{array} \]
    (FPCore (x y z)
     :precision binary64
     (if (or (<= z -0.38) (not (<= z 1700000000.0))) (- z) (* (log (/ x y)) x)))
    double code(double x, double y, double z) {
    	double tmp;
    	if ((z <= -0.38) || !(z <= 1700000000.0)) {
    		tmp = -z;
    	} else {
    		tmp = log((x / y)) * x;
    	}
    	return tmp;
    }
    
    module fmin_fmax_functions
        implicit none
        private
        public fmax
        public fmin
    
        interface fmax
            module procedure fmax88
            module procedure fmax44
            module procedure fmax84
            module procedure fmax48
        end interface
        interface fmin
            module procedure fmin88
            module procedure fmin44
            module procedure fmin84
            module procedure fmin48
        end interface
    contains
        real(8) function fmax88(x, y) result (res)
            real(8), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(x, max(x, y), y /= y), x /= x)
        end function
        real(4) function fmax44(x, y) result (res)
            real(4), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(y, merge(x, max(x, y), y /= y), x /= x)
        end function
        real(8) function fmax84(x, y) result(res)
            real(8), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
        end function
        real(8) function fmax48(x, y) result(res)
            real(4), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
        end function
        real(8) function fmin88(x, y) result (res)
            real(8), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(x, min(x, y), y /= y), x /= x)
        end function
        real(4) function fmin44(x, y) result (res)
            real(4), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(y, merge(x, min(x, y), y /= y), x /= x)
        end function
        real(8) function fmin84(x, y) result(res)
            real(8), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
        end function
        real(8) function fmin48(x, y) result(res)
            real(4), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
        end function
    end module
    
    real(8) function code(x, y, z)
    use fmin_fmax_functions
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        real(8), intent (in) :: z
        real(8) :: tmp
        if ((z <= (-0.38d0)) .or. (.not. (z <= 1700000000.0d0))) then
            tmp = -z
        else
            tmp = log((x / y)) * x
        end if
        code = tmp
    end function
    
    public static double code(double x, double y, double z) {
    	double tmp;
    	if ((z <= -0.38) || !(z <= 1700000000.0)) {
    		tmp = -z;
    	} else {
    		tmp = Math.log((x / y)) * x;
    	}
    	return tmp;
    }
    
    def code(x, y, z):
    	tmp = 0
    	if (z <= -0.38) or not (z <= 1700000000.0):
    		tmp = -z
    	else:
    		tmp = math.log((x / y)) * x
    	return tmp
    
    function code(x, y, z)
    	tmp = 0.0
    	if ((z <= -0.38) || !(z <= 1700000000.0))
    		tmp = Float64(-z);
    	else
    		tmp = Float64(log(Float64(x / y)) * x);
    	end
    	return tmp
    end
    
    function tmp_2 = code(x, y, z)
    	tmp = 0.0;
    	if ((z <= -0.38) || ~((z <= 1700000000.0)))
    		tmp = -z;
    	else
    		tmp = log((x / y)) * x;
    	end
    	tmp_2 = tmp;
    end
    
    code[x_, y_, z_] := If[Or[LessEqual[z, -0.38], N[Not[LessEqual[z, 1700000000.0]], $MachinePrecision]], (-z), N[(N[Log[N[(x / y), $MachinePrecision]], $MachinePrecision] * x), $MachinePrecision]]
    
    \begin{array}{l}
    
    \\
    \begin{array}{l}
    \mathbf{if}\;z \leq -0.38 \lor \neg \left(z \leq 1700000000\right):\\
    \;\;\;\;-z\\
    
    \mathbf{else}:\\
    \;\;\;\;\log \left(\frac{x}{y}\right) \cdot x\\
    
    
    \end{array}
    \end{array}
    
    Derivation
    1. Split input into 2 regimes
    2. if z < -0.38 or 1.7e9 < z

      1. Initial program 78.6%

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

        \[\leadsto \color{blue}{-1 \cdot z} \]
      4. Step-by-step derivation
        1. mul-1-negN/A

          \[\leadsto \color{blue}{\mathsf{neg}\left(z\right)} \]
        2. lower-neg.f6479.1

          \[\leadsto \color{blue}{-z} \]
      5. Applied rewrites79.1%

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

      if -0.38 < z < 1.7e9

      1. Initial program 79.8%

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

        \[\leadsto \color{blue}{x \cdot \log \left(\frac{x}{y}\right)} \]
      4. Step-by-step derivation
        1. *-commutativeN/A

          \[\leadsto \color{blue}{\log \left(\frac{x}{y}\right) \cdot x} \]
        2. lower-*.f64N/A

          \[\leadsto \color{blue}{\log \left(\frac{x}{y}\right) \cdot x} \]
        3. lower-log.f64N/A

          \[\leadsto \color{blue}{\log \left(\frac{x}{y}\right)} \cdot x \]
        4. lower-/.f6466.1

          \[\leadsto \log \color{blue}{\left(\frac{x}{y}\right)} \cdot x \]
      5. Applied rewrites66.1%

        \[\leadsto \color{blue}{\log \left(\frac{x}{y}\right) \cdot x} \]
    3. Recombined 2 regimes into one program.
    4. Final simplification72.7%

      \[\leadsto \begin{array}{l} \mathbf{if}\;z \leq -0.38 \lor \neg \left(z \leq 1700000000\right):\\ \;\;\;\;-z\\ \mathbf{else}:\\ \;\;\;\;\log \left(\frac{x}{y}\right) \cdot x\\ \end{array} \]
    5. Add Preprocessing

    Alternative 6: 51.1% accurate, 40.0× speedup?

    \[\begin{array}{l} \\ -z \end{array} \]
    (FPCore (x y z) :precision binary64 (- z))
    double code(double x, double y, double z) {
    	return -z;
    }
    
    module fmin_fmax_functions
        implicit none
        private
        public fmax
        public fmin
    
        interface fmax
            module procedure fmax88
            module procedure fmax44
            module procedure fmax84
            module procedure fmax48
        end interface
        interface fmin
            module procedure fmin88
            module procedure fmin44
            module procedure fmin84
            module procedure fmin48
        end interface
    contains
        real(8) function fmax88(x, y) result (res)
            real(8), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(x, max(x, y), y /= y), x /= x)
        end function
        real(4) function fmax44(x, y) result (res)
            real(4), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(y, merge(x, max(x, y), y /= y), x /= x)
        end function
        real(8) function fmax84(x, y) result(res)
            real(8), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
        end function
        real(8) function fmax48(x, y) result(res)
            real(4), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
        end function
        real(8) function fmin88(x, y) result (res)
            real(8), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(x, min(x, y), y /= y), x /= x)
        end function
        real(4) function fmin44(x, y) result (res)
            real(4), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(y, merge(x, min(x, y), y /= y), x /= x)
        end function
        real(8) function fmin84(x, y) result(res)
            real(8), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
        end function
        real(8) function fmin48(x, y) result(res)
            real(4), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
        end function
    end module
    
    real(8) function code(x, y, z)
    use fmin_fmax_functions
        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 79.2%

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

      \[\leadsto \color{blue}{-1 \cdot z} \]
    4. Step-by-step derivation
      1. mul-1-negN/A

        \[\leadsto \color{blue}{\mathsf{neg}\left(z\right)} \]
      2. lower-neg.f6450.7

        \[\leadsto \color{blue}{-z} \]
    5. Applied rewrites50.7%

      \[\leadsto \color{blue}{-z} \]
    6. Add Preprocessing

    Developer Target 1: 88.4% accurate, 0.6× 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;
    }
    
    module fmin_fmax_functions
        implicit none
        private
        public fmax
        public fmin
    
        interface fmax
            module procedure fmax88
            module procedure fmax44
            module procedure fmax84
            module procedure fmax48
        end interface
        interface fmin
            module procedure fmin88
            module procedure fmin44
            module procedure fmin84
            module procedure fmin48
        end interface
    contains
        real(8) function fmax88(x, y) result (res)
            real(8), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(x, max(x, y), y /= y), x /= x)
        end function
        real(4) function fmax44(x, y) result (res)
            real(4), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(y, merge(x, max(x, y), y /= y), x /= x)
        end function
        real(8) function fmax84(x, y) result(res)
            real(8), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
        end function
        real(8) function fmax48(x, y) result(res)
            real(4), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
        end function
        real(8) function fmin88(x, y) result (res)
            real(8), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(x, min(x, y), y /= y), x /= x)
        end function
        real(4) function fmin44(x, y) result (res)
            real(4), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(y, merge(x, min(x, y), y /= y), x /= x)
        end function
        real(8) function fmin84(x, y) result(res)
            real(8), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
        end function
        real(8) function fmin48(x, y) result(res)
            real(4), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
        end function
    end module
    
    real(8) function code(x, y, z)
    use fmin_fmax_functions
        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 2025008 
    (FPCore (x y z)
      :name "Numeric.SpecFunctions.Extra:bd0 from math-functions-0.1.5.2"
      :precision binary64
    
      :alt
      (! :herbie-platform default (if (< y 7595077799083773/100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000) (- (* x (log (/ x y))) z) (- (* x (- (log x) (log y))) z)))
    
      (- (* x (log (/ x y))) z))