VandenBroeck and Keller, Equation (20)

Percentage Accurate: 6.6% → 99.1%
Time: 9.5s
Alternatives: 8
Speedup: 4.8×

Specification

?
\[\begin{array}{l} \\ \begin{array}{l} t_0 := \frac{\pi}{4} \cdot f\\ t_1 := e^{t\_0}\\ t_2 := e^{-t\_0}\\ -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{t\_1 + t\_2}{t\_1 - t\_2}\right) \end{array} \end{array} \]
(FPCore (f)
 :precision binary64
 (let* ((t_0 (* (/ PI 4.0) f)) (t_1 (exp t_0)) (t_2 (exp (- t_0))))
   (- (* (/ 1.0 (/ PI 4.0)) (log (/ (+ t_1 t_2) (- t_1 t_2)))))))
double code(double f) {
	double t_0 = (((double) M_PI) / 4.0) * f;
	double t_1 = exp(t_0);
	double t_2 = exp(-t_0);
	return -((1.0 / (((double) M_PI) / 4.0)) * log(((t_1 + t_2) / (t_1 - t_2))));
}
public static double code(double f) {
	double t_0 = (Math.PI / 4.0) * f;
	double t_1 = Math.exp(t_0);
	double t_2 = Math.exp(-t_0);
	return -((1.0 / (Math.PI / 4.0)) * Math.log(((t_1 + t_2) / (t_1 - t_2))));
}
def code(f):
	t_0 = (math.pi / 4.0) * f
	t_1 = math.exp(t_0)
	t_2 = math.exp(-t_0)
	return -((1.0 / (math.pi / 4.0)) * math.log(((t_1 + t_2) / (t_1 - t_2))))
function code(f)
	t_0 = Float64(Float64(pi / 4.0) * f)
	t_1 = exp(t_0)
	t_2 = exp(Float64(-t_0))
	return Float64(-Float64(Float64(1.0 / Float64(pi / 4.0)) * log(Float64(Float64(t_1 + t_2) / Float64(t_1 - t_2)))))
end
function tmp = code(f)
	t_0 = (pi / 4.0) * f;
	t_1 = exp(t_0);
	t_2 = exp(-t_0);
	tmp = -((1.0 / (pi / 4.0)) * log(((t_1 + t_2) / (t_1 - t_2))));
end
code[f_] := Block[{t$95$0 = N[(N[(Pi / 4.0), $MachinePrecision] * f), $MachinePrecision]}, Block[{t$95$1 = N[Exp[t$95$0], $MachinePrecision]}, Block[{t$95$2 = N[Exp[(-t$95$0)], $MachinePrecision]}, (-N[(N[(1.0 / N[(Pi / 4.0), $MachinePrecision]), $MachinePrecision] * N[Log[N[(N[(t$95$1 + t$95$2), $MachinePrecision] / N[(t$95$1 - t$95$2), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision])]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \frac{\pi}{4} \cdot f\\
t_1 := e^{t\_0}\\
t_2 := e^{-t\_0}\\
-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{t\_1 + t\_2}{t\_1 - t\_2}\right)
\end{array}
\end{array}

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 8 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: 6.6% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \frac{\pi}{4} \cdot f\\ t_1 := e^{t\_0}\\ t_2 := e^{-t\_0}\\ -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{t\_1 + t\_2}{t\_1 - t\_2}\right) \end{array} \end{array} \]
(FPCore (f)
 :precision binary64
 (let* ((t_0 (* (/ PI 4.0) f)) (t_1 (exp t_0)) (t_2 (exp (- t_0))))
   (- (* (/ 1.0 (/ PI 4.0)) (log (/ (+ t_1 t_2) (- t_1 t_2)))))))
double code(double f) {
	double t_0 = (((double) M_PI) / 4.0) * f;
	double t_1 = exp(t_0);
	double t_2 = exp(-t_0);
	return -((1.0 / (((double) M_PI) / 4.0)) * log(((t_1 + t_2) / (t_1 - t_2))));
}
public static double code(double f) {
	double t_0 = (Math.PI / 4.0) * f;
	double t_1 = Math.exp(t_0);
	double t_2 = Math.exp(-t_0);
	return -((1.0 / (Math.PI / 4.0)) * Math.log(((t_1 + t_2) / (t_1 - t_2))));
}
def code(f):
	t_0 = (math.pi / 4.0) * f
	t_1 = math.exp(t_0)
	t_2 = math.exp(-t_0)
	return -((1.0 / (math.pi / 4.0)) * math.log(((t_1 + t_2) / (t_1 - t_2))))
function code(f)
	t_0 = Float64(Float64(pi / 4.0) * f)
	t_1 = exp(t_0)
	t_2 = exp(Float64(-t_0))
	return Float64(-Float64(Float64(1.0 / Float64(pi / 4.0)) * log(Float64(Float64(t_1 + t_2) / Float64(t_1 - t_2)))))
end
function tmp = code(f)
	t_0 = (pi / 4.0) * f;
	t_1 = exp(t_0);
	t_2 = exp(-t_0);
	tmp = -((1.0 / (pi / 4.0)) * log(((t_1 + t_2) / (t_1 - t_2))));
end
code[f_] := Block[{t$95$0 = N[(N[(Pi / 4.0), $MachinePrecision] * f), $MachinePrecision]}, Block[{t$95$1 = N[Exp[t$95$0], $MachinePrecision]}, Block[{t$95$2 = N[Exp[(-t$95$0)], $MachinePrecision]}, (-N[(N[(1.0 / N[(Pi / 4.0), $MachinePrecision]), $MachinePrecision] * N[Log[N[(N[(t$95$1 + t$95$2), $MachinePrecision] / N[(t$95$1 - t$95$2), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision])]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \frac{\pi}{4} \cdot f\\
t_1 := e^{t\_0}\\
t_2 := e^{-t\_0}\\
-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{t\_1 + t\_2}{t\_1 - t\_2}\right)
\end{array}
\end{array}

Alternative 1: 99.1% accurate, 1.4× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := e^{\left(f \cdot \pi\right) \cdot -0.25}\\ t_1 := \left(f \cdot \pi\right) \cdot 0.25\\ \mathbf{if}\;f \leq 24:\\ \;\;\;\;\frac{\log 2 + \log \left(\frac{\cosh t\_1}{\sinh t\_1 \cdot 2}\right)}{\pi} \cdot -4\\ \mathbf{else}:\\ \;\;\;\;\frac{4}{\pi} \cdot \left(-\log \left(\frac{t\_0 + 1}{1 - t\_0}\right)\right)\\ \end{array} \end{array} \]
(FPCore (f)
 :precision binary64
 (let* ((t_0 (exp (* (* f PI) -0.25))) (t_1 (* (* f PI) 0.25)))
   (if (<= f 24.0)
     (* (/ (+ (log 2.0) (log (/ (cosh t_1) (* (sinh t_1) 2.0)))) PI) -4.0)
     (* (/ 4.0 PI) (- (log (/ (+ t_0 1.0) (- 1.0 t_0))))))))
double code(double f) {
	double t_0 = exp(((f * ((double) M_PI)) * -0.25));
	double t_1 = (f * ((double) M_PI)) * 0.25;
	double tmp;
	if (f <= 24.0) {
		tmp = ((log(2.0) + log((cosh(t_1) / (sinh(t_1) * 2.0)))) / ((double) M_PI)) * -4.0;
	} else {
		tmp = (4.0 / ((double) M_PI)) * -log(((t_0 + 1.0) / (1.0 - t_0)));
	}
	return tmp;
}
public static double code(double f) {
	double t_0 = Math.exp(((f * Math.PI) * -0.25));
	double t_1 = (f * Math.PI) * 0.25;
	double tmp;
	if (f <= 24.0) {
		tmp = ((Math.log(2.0) + Math.log((Math.cosh(t_1) / (Math.sinh(t_1) * 2.0)))) / Math.PI) * -4.0;
	} else {
		tmp = (4.0 / Math.PI) * -Math.log(((t_0 + 1.0) / (1.0 - t_0)));
	}
	return tmp;
}
def code(f):
	t_0 = math.exp(((f * math.pi) * -0.25))
	t_1 = (f * math.pi) * 0.25
	tmp = 0
	if f <= 24.0:
		tmp = ((math.log(2.0) + math.log((math.cosh(t_1) / (math.sinh(t_1) * 2.0)))) / math.pi) * -4.0
	else:
		tmp = (4.0 / math.pi) * -math.log(((t_0 + 1.0) / (1.0 - t_0)))
	return tmp
function code(f)
	t_0 = exp(Float64(Float64(f * pi) * -0.25))
	t_1 = Float64(Float64(f * pi) * 0.25)
	tmp = 0.0
	if (f <= 24.0)
		tmp = Float64(Float64(Float64(log(2.0) + log(Float64(cosh(t_1) / Float64(sinh(t_1) * 2.0)))) / pi) * -4.0);
	else
		tmp = Float64(Float64(4.0 / pi) * Float64(-log(Float64(Float64(t_0 + 1.0) / Float64(1.0 - t_0)))));
	end
	return tmp
end
function tmp_2 = code(f)
	t_0 = exp(((f * pi) * -0.25));
	t_1 = (f * pi) * 0.25;
	tmp = 0.0;
	if (f <= 24.0)
		tmp = ((log(2.0) + log((cosh(t_1) / (sinh(t_1) * 2.0)))) / pi) * -4.0;
	else
		tmp = (4.0 / pi) * -log(((t_0 + 1.0) / (1.0 - t_0)));
	end
	tmp_2 = tmp;
end
code[f_] := Block[{t$95$0 = N[Exp[N[(N[(f * Pi), $MachinePrecision] * -0.25), $MachinePrecision]], $MachinePrecision]}, Block[{t$95$1 = N[(N[(f * Pi), $MachinePrecision] * 0.25), $MachinePrecision]}, If[LessEqual[f, 24.0], N[(N[(N[(N[Log[2.0], $MachinePrecision] + N[Log[N[(N[Cosh[t$95$1], $MachinePrecision] / N[(N[Sinh[t$95$1], $MachinePrecision] * 2.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / Pi), $MachinePrecision] * -4.0), $MachinePrecision], N[(N[(4.0 / Pi), $MachinePrecision] * (-N[Log[N[(N[(t$95$0 + 1.0), $MachinePrecision] / N[(1.0 - t$95$0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision])), $MachinePrecision]]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := e^{\left(f \cdot \pi\right) \cdot -0.25}\\
t_1 := \left(f \cdot \pi\right) \cdot 0.25\\
\mathbf{if}\;f \leq 24:\\
\;\;\;\;\frac{\log 2 + \log \left(\frac{\cosh t\_1}{\sinh t\_1 \cdot 2}\right)}{\pi} \cdot -4\\

\mathbf{else}:\\
\;\;\;\;\frac{4}{\pi} \cdot \left(-\log \left(\frac{t\_0 + 1}{1 - t\_0}\right)\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if f < 24

    1. Initial program 6.6%

      \[-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{e^{\frac{\pi}{4} \cdot f} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
    2. Taylor expanded in f around inf

      \[\leadsto \color{blue}{-4 \cdot \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)}} \]
    3. Step-by-step derivation
      1. *-commutativeN/A

        \[\leadsto \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
      2. lower-*.f64N/A

        \[\leadsto \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
    4. Applied rewrites96.9%

      \[\leadsto \color{blue}{\frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot -0.25\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot 0.25\right)}\right)}{\pi} \cdot -4} \]
    5. Step-by-step derivation
      1. lift-log.f64N/A

        \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
      2. lift-/.f64N/A

        \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
      3. lift-*.f64N/A

        \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
      4. lift-cosh.f64N/A

        \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
      5. lift-*.f64N/A

        \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
      6. lift-PI.f64N/A

        \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
      7. lift-*.f64N/A

        \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
      8. lift-*.f64N/A

        \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
      9. lift-sinh.f64N/A

        \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
      10. lift-*.f64N/A

        \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
      11. lift-PI.f64N/A

        \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
      12. lift-*.f64N/A

        \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
    6. Applied rewrites96.8%

      \[\leadsto \frac{\log 2 + \log \left(\frac{\cosh \left(\left(f \cdot \pi\right) \cdot 0.25\right)}{\sinh \left(\left(f \cdot \pi\right) \cdot 0.25\right) \cdot 2}\right)}{\pi} \cdot -4 \]

    if 24 < f

    1. Initial program 6.6%

      \[-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{e^{\frac{\pi}{4} \cdot f} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
    2. Taylor expanded in f around 0

      \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{\color{blue}{1} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
    3. Step-by-step derivation
      1. Applied rewrites5.3%

        \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{\color{blue}{1} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
      2. Taylor expanded in f around 0

        \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{-\frac{\pi}{4} \cdot f}}{\color{blue}{1} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
      3. Step-by-step derivation
        1. Applied rewrites6.5%

          \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{-\frac{\pi}{4} \cdot f}}{\color{blue}{1} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
        2. Taylor expanded in f around inf

          \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + \color{blue}{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
        3. Step-by-step derivation
          1. distribute-lft-neg-inN/A

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(\mathsf{neg}\left(\frac{1}{4}\right)\right) \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
          2. metadata-evalN/A

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\frac{-1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
          3. lower-exp.f64N/A

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\frac{-1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
          4. *-commutativeN/A

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
          5. lower-*.f64N/A

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
          6. lower-*.f64N/A

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
          7. lift-PI.f646.5

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot -0.25}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
        4. Applied rewrites6.5%

          \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + \color{blue}{e^{\left(f \cdot \pi\right) \cdot -0.25}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
        5. Taylor expanded in f around inf

          \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - \color{blue}{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}}\right) \]
        6. Step-by-step derivation
          1. distribute-lft-neg-inN/A

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(\mathsf{neg}\left(\frac{1}{4}\right)\right) \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}\right) \]
          2. metadata-evalN/A

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\frac{-1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}\right) \]
          3. lower-exp.f64N/A

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\frac{-1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}\right) \]
          4. *-commutativeN/A

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}\right) \]
          5. lower-*.f64N/A

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}\right) \]
          6. lower-*.f64N/A

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}\right) \]
          7. lift-PI.f646.5

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot -0.25}}{1 - e^{\left(f \cdot \pi\right) \cdot -0.25}}\right) \]
        7. Applied rewrites6.5%

          \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot -0.25}}{1 - \color{blue}{e^{\left(f \cdot \pi\right) \cdot -0.25}}}\right) \]
        8. Step-by-step derivation
          1. lift-neg.f64N/A

            \[\leadsto \color{blue}{\mathsf{neg}\left(\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right)} \]
          2. lift-*.f64N/A

            \[\leadsto \mathsf{neg}\left(\color{blue}{\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)}\right) \]
          3. distribute-rgt-neg-inN/A

            \[\leadsto \color{blue}{\frac{1}{\frac{\pi}{4}} \cdot \left(\mathsf{neg}\left(\log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right)\right)} \]
        9. Applied rewrites6.5%

          \[\leadsto \color{blue}{\left(\frac{1}{\pi} \cdot 4\right) \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot -0.25} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot -0.25}}\right)\right)} \]
        10. Step-by-step derivation
          1. lift-*.f64N/A

            \[\leadsto \color{blue}{\left(\frac{1}{\pi} \cdot 4\right)} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
          2. lift-PI.f64N/A

            \[\leadsto \left(\frac{1}{\color{blue}{\mathsf{PI}\left(\right)}} \cdot 4\right) \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
          3. lift-/.f64N/A

            \[\leadsto \left(\color{blue}{\frac{1}{\mathsf{PI}\left(\right)}} \cdot 4\right) \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
          4. associate-*l/N/A

            \[\leadsto \color{blue}{\frac{1 \cdot 4}{\mathsf{PI}\left(\right)}} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
          5. metadata-evalN/A

            \[\leadsto \frac{\color{blue}{4}}{\mathsf{PI}\left(\right)} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
          6. lower-/.f64N/A

            \[\leadsto \color{blue}{\frac{4}{\mathsf{PI}\left(\right)}} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
          7. lift-PI.f646.5

            \[\leadsto \frac{4}{\color{blue}{\pi}} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot -0.25} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot -0.25}}\right)\right) \]
        11. Applied rewrites6.5%

          \[\leadsto \color{blue}{\frac{4}{\pi} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot -0.25} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot -0.25}}\right)\right)} \]
      4. Recombined 2 regimes into one program.
      5. Add Preprocessing

      Alternative 2: 99.0% accurate, 1.6× speedup?

      \[\begin{array}{l} \\ \begin{array}{l} t_0 := e^{\left(f \cdot \pi\right) \cdot -0.25}\\ t_1 := \left(f \cdot \pi\right) \cdot 0.25\\ \mathbf{if}\;f \leq 24:\\ \;\;\;\;\frac{\log \cosh t\_1 - \log \sinh t\_1}{\pi} \cdot -4\\ \mathbf{else}:\\ \;\;\;\;\frac{4}{\pi} \cdot \left(-\log \left(\frac{t\_0 + 1}{1 - t\_0}\right)\right)\\ \end{array} \end{array} \]
      (FPCore (f)
       :precision binary64
       (let* ((t_0 (exp (* (* f PI) -0.25))) (t_1 (* (* f PI) 0.25)))
         (if (<= f 24.0)
           (* (/ (- (log (cosh t_1)) (log (sinh t_1))) PI) -4.0)
           (* (/ 4.0 PI) (- (log (/ (+ t_0 1.0) (- 1.0 t_0))))))))
      double code(double f) {
      	double t_0 = exp(((f * ((double) M_PI)) * -0.25));
      	double t_1 = (f * ((double) M_PI)) * 0.25;
      	double tmp;
      	if (f <= 24.0) {
      		tmp = ((log(cosh(t_1)) - log(sinh(t_1))) / ((double) M_PI)) * -4.0;
      	} else {
      		tmp = (4.0 / ((double) M_PI)) * -log(((t_0 + 1.0) / (1.0 - t_0)));
      	}
      	return tmp;
      }
      
      public static double code(double f) {
      	double t_0 = Math.exp(((f * Math.PI) * -0.25));
      	double t_1 = (f * Math.PI) * 0.25;
      	double tmp;
      	if (f <= 24.0) {
      		tmp = ((Math.log(Math.cosh(t_1)) - Math.log(Math.sinh(t_1))) / Math.PI) * -4.0;
      	} else {
      		tmp = (4.0 / Math.PI) * -Math.log(((t_0 + 1.0) / (1.0 - t_0)));
      	}
      	return tmp;
      }
      
      def code(f):
      	t_0 = math.exp(((f * math.pi) * -0.25))
      	t_1 = (f * math.pi) * 0.25
      	tmp = 0
      	if f <= 24.0:
      		tmp = ((math.log(math.cosh(t_1)) - math.log(math.sinh(t_1))) / math.pi) * -4.0
      	else:
      		tmp = (4.0 / math.pi) * -math.log(((t_0 + 1.0) / (1.0 - t_0)))
      	return tmp
      
      function code(f)
      	t_0 = exp(Float64(Float64(f * pi) * -0.25))
      	t_1 = Float64(Float64(f * pi) * 0.25)
      	tmp = 0.0
      	if (f <= 24.0)
      		tmp = Float64(Float64(Float64(log(cosh(t_1)) - log(sinh(t_1))) / pi) * -4.0);
      	else
      		tmp = Float64(Float64(4.0 / pi) * Float64(-log(Float64(Float64(t_0 + 1.0) / Float64(1.0 - t_0)))));
      	end
      	return tmp
      end
      
      function tmp_2 = code(f)
      	t_0 = exp(((f * pi) * -0.25));
      	t_1 = (f * pi) * 0.25;
      	tmp = 0.0;
      	if (f <= 24.0)
      		tmp = ((log(cosh(t_1)) - log(sinh(t_1))) / pi) * -4.0;
      	else
      		tmp = (4.0 / pi) * -log(((t_0 + 1.0) / (1.0 - t_0)));
      	end
      	tmp_2 = tmp;
      end
      
      code[f_] := Block[{t$95$0 = N[Exp[N[(N[(f * Pi), $MachinePrecision] * -0.25), $MachinePrecision]], $MachinePrecision]}, Block[{t$95$1 = N[(N[(f * Pi), $MachinePrecision] * 0.25), $MachinePrecision]}, If[LessEqual[f, 24.0], N[(N[(N[(N[Log[N[Cosh[t$95$1], $MachinePrecision]], $MachinePrecision] - N[Log[N[Sinh[t$95$1], $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / Pi), $MachinePrecision] * -4.0), $MachinePrecision], N[(N[(4.0 / Pi), $MachinePrecision] * (-N[Log[N[(N[(t$95$0 + 1.0), $MachinePrecision] / N[(1.0 - t$95$0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision])), $MachinePrecision]]]]
      
      \begin{array}{l}
      
      \\
      \begin{array}{l}
      t_0 := e^{\left(f \cdot \pi\right) \cdot -0.25}\\
      t_1 := \left(f \cdot \pi\right) \cdot 0.25\\
      \mathbf{if}\;f \leq 24:\\
      \;\;\;\;\frac{\log \cosh t\_1 - \log \sinh t\_1}{\pi} \cdot -4\\
      
      \mathbf{else}:\\
      \;\;\;\;\frac{4}{\pi} \cdot \left(-\log \left(\frac{t\_0 + 1}{1 - t\_0}\right)\right)\\
      
      
      \end{array}
      \end{array}
      
      Derivation
      1. Split input into 2 regimes
      2. if f < 24

        1. Initial program 6.6%

          \[-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{e^{\frac{\pi}{4} \cdot f} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
        2. Taylor expanded in f around inf

          \[\leadsto \color{blue}{-4 \cdot \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)}} \]
        3. Step-by-step derivation
          1. *-commutativeN/A

            \[\leadsto \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
          2. lower-*.f64N/A

            \[\leadsto \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
        4. Applied rewrites96.9%

          \[\leadsto \color{blue}{\frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot -0.25\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot 0.25\right)}\right)}{\pi} \cdot -4} \]
        5. Step-by-step derivation
          1. lift-log.f64N/A

            \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
          2. lift-/.f64N/A

            \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
          3. lift-*.f64N/A

            \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
          4. lift-cosh.f64N/A

            \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
          5. lift-*.f64N/A

            \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
          6. lift-PI.f64N/A

            \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
          7. lift-*.f64N/A

            \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
          8. lift-*.f64N/A

            \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
          9. lift-sinh.f64N/A

            \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
          10. lift-*.f64N/A

            \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
          11. lift-PI.f64N/A

            \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
          12. lift-*.f64N/A

            \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
          13. associate-/r*N/A

            \[\leadsto \frac{\log \left(\frac{\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2}}{\sinh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
        6. Applied rewrites96.9%

          \[\leadsto \frac{\log \cosh \left(\left(f \cdot \pi\right) \cdot 0.25\right) - \log \sinh \left(\left(f \cdot \pi\right) \cdot 0.25\right)}{\pi} \cdot -4 \]

        if 24 < f

        1. Initial program 6.6%

          \[-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{e^{\frac{\pi}{4} \cdot f} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
        2. Taylor expanded in f around 0

          \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{\color{blue}{1} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
        3. Step-by-step derivation
          1. Applied rewrites5.3%

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{\color{blue}{1} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
          2. Taylor expanded in f around 0

            \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{-\frac{\pi}{4} \cdot f}}{\color{blue}{1} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
          3. Step-by-step derivation
            1. Applied rewrites6.5%

              \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{-\frac{\pi}{4} \cdot f}}{\color{blue}{1} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
            2. Taylor expanded in f around inf

              \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + \color{blue}{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
            3. Step-by-step derivation
              1. distribute-lft-neg-inN/A

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(\mathsf{neg}\left(\frac{1}{4}\right)\right) \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
              2. metadata-evalN/A

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\frac{-1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
              3. lower-exp.f64N/A

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\frac{-1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
              4. *-commutativeN/A

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
              5. lower-*.f64N/A

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
              6. lower-*.f64N/A

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
              7. lift-PI.f646.5

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot -0.25}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
            4. Applied rewrites6.5%

              \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + \color{blue}{e^{\left(f \cdot \pi\right) \cdot -0.25}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
            5. Taylor expanded in f around inf

              \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - \color{blue}{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}}\right) \]
            6. Step-by-step derivation
              1. distribute-lft-neg-inN/A

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(\mathsf{neg}\left(\frac{1}{4}\right)\right) \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}\right) \]
              2. metadata-evalN/A

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\frac{-1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}\right) \]
              3. lower-exp.f64N/A

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\frac{-1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}\right) \]
              4. *-commutativeN/A

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}\right) \]
              5. lower-*.f64N/A

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}\right) \]
              6. lower-*.f64N/A

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}\right) \]
              7. lift-PI.f646.5

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot -0.25}}{1 - e^{\left(f \cdot \pi\right) \cdot -0.25}}\right) \]
            7. Applied rewrites6.5%

              \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot -0.25}}{1 - \color{blue}{e^{\left(f \cdot \pi\right) \cdot -0.25}}}\right) \]
            8. Step-by-step derivation
              1. lift-neg.f64N/A

                \[\leadsto \color{blue}{\mathsf{neg}\left(\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right)} \]
              2. lift-*.f64N/A

                \[\leadsto \mathsf{neg}\left(\color{blue}{\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)}\right) \]
              3. distribute-rgt-neg-inN/A

                \[\leadsto \color{blue}{\frac{1}{\frac{\pi}{4}} \cdot \left(\mathsf{neg}\left(\log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right)\right)} \]
            9. Applied rewrites6.5%

              \[\leadsto \color{blue}{\left(\frac{1}{\pi} \cdot 4\right) \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot -0.25} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot -0.25}}\right)\right)} \]
            10. Step-by-step derivation
              1. lift-*.f64N/A

                \[\leadsto \color{blue}{\left(\frac{1}{\pi} \cdot 4\right)} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
              2. lift-PI.f64N/A

                \[\leadsto \left(\frac{1}{\color{blue}{\mathsf{PI}\left(\right)}} \cdot 4\right) \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
              3. lift-/.f64N/A

                \[\leadsto \left(\color{blue}{\frac{1}{\mathsf{PI}\left(\right)}} \cdot 4\right) \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
              4. associate-*l/N/A

                \[\leadsto \color{blue}{\frac{1 \cdot 4}{\mathsf{PI}\left(\right)}} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
              5. metadata-evalN/A

                \[\leadsto \frac{\color{blue}{4}}{\mathsf{PI}\left(\right)} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
              6. lower-/.f64N/A

                \[\leadsto \color{blue}{\frac{4}{\mathsf{PI}\left(\right)}} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
              7. lift-PI.f646.5

                \[\leadsto \frac{4}{\color{blue}{\pi}} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot -0.25} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot -0.25}}\right)\right) \]
            11. Applied rewrites6.5%

              \[\leadsto \color{blue}{\frac{4}{\pi} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot -0.25} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot -0.25}}\right)\right)} \]
          4. Recombined 2 regimes into one program.
          5. Add Preprocessing

          Alternative 3: 99.0% accurate, 1.6× speedup?

          \[\begin{array}{l} \\ \begin{array}{l} t_0 := e^{\left(f \cdot \pi\right) \cdot -0.25}\\ t_1 := \left(f \cdot \pi\right) \cdot 0.25\\ \mathbf{if}\;f \leq 24:\\ \;\;\;\;\frac{\log \left(\frac{\cosh t\_1}{\sinh t\_1}\right)}{\pi} \cdot -4\\ \mathbf{else}:\\ \;\;\;\;\frac{4}{\pi} \cdot \left(-\log \left(\frac{t\_0 + 1}{1 - t\_0}\right)\right)\\ \end{array} \end{array} \]
          (FPCore (f)
           :precision binary64
           (let* ((t_0 (exp (* (* f PI) -0.25))) (t_1 (* (* f PI) 0.25)))
             (if (<= f 24.0)
               (* (/ (log (/ (cosh t_1) (sinh t_1))) PI) -4.0)
               (* (/ 4.0 PI) (- (log (/ (+ t_0 1.0) (- 1.0 t_0))))))))
          double code(double f) {
          	double t_0 = exp(((f * ((double) M_PI)) * -0.25));
          	double t_1 = (f * ((double) M_PI)) * 0.25;
          	double tmp;
          	if (f <= 24.0) {
          		tmp = (log((cosh(t_1) / sinh(t_1))) / ((double) M_PI)) * -4.0;
          	} else {
          		tmp = (4.0 / ((double) M_PI)) * -log(((t_0 + 1.0) / (1.0 - t_0)));
          	}
          	return tmp;
          }
          
          public static double code(double f) {
          	double t_0 = Math.exp(((f * Math.PI) * -0.25));
          	double t_1 = (f * Math.PI) * 0.25;
          	double tmp;
          	if (f <= 24.0) {
          		tmp = (Math.log((Math.cosh(t_1) / Math.sinh(t_1))) / Math.PI) * -4.0;
          	} else {
          		tmp = (4.0 / Math.PI) * -Math.log(((t_0 + 1.0) / (1.0 - t_0)));
          	}
          	return tmp;
          }
          
          def code(f):
          	t_0 = math.exp(((f * math.pi) * -0.25))
          	t_1 = (f * math.pi) * 0.25
          	tmp = 0
          	if f <= 24.0:
          		tmp = (math.log((math.cosh(t_1) / math.sinh(t_1))) / math.pi) * -4.0
          	else:
          		tmp = (4.0 / math.pi) * -math.log(((t_0 + 1.0) / (1.0 - t_0)))
          	return tmp
          
          function code(f)
          	t_0 = exp(Float64(Float64(f * pi) * -0.25))
          	t_1 = Float64(Float64(f * pi) * 0.25)
          	tmp = 0.0
          	if (f <= 24.0)
          		tmp = Float64(Float64(log(Float64(cosh(t_1) / sinh(t_1))) / pi) * -4.0);
          	else
          		tmp = Float64(Float64(4.0 / pi) * Float64(-log(Float64(Float64(t_0 + 1.0) / Float64(1.0 - t_0)))));
          	end
          	return tmp
          end
          
          function tmp_2 = code(f)
          	t_0 = exp(((f * pi) * -0.25));
          	t_1 = (f * pi) * 0.25;
          	tmp = 0.0;
          	if (f <= 24.0)
          		tmp = (log((cosh(t_1) / sinh(t_1))) / pi) * -4.0;
          	else
          		tmp = (4.0 / pi) * -log(((t_0 + 1.0) / (1.0 - t_0)));
          	end
          	tmp_2 = tmp;
          end
          
          code[f_] := Block[{t$95$0 = N[Exp[N[(N[(f * Pi), $MachinePrecision] * -0.25), $MachinePrecision]], $MachinePrecision]}, Block[{t$95$1 = N[(N[(f * Pi), $MachinePrecision] * 0.25), $MachinePrecision]}, If[LessEqual[f, 24.0], N[(N[(N[Log[N[(N[Cosh[t$95$1], $MachinePrecision] / N[Sinh[t$95$1], $MachinePrecision]), $MachinePrecision]], $MachinePrecision] / Pi), $MachinePrecision] * -4.0), $MachinePrecision], N[(N[(4.0 / Pi), $MachinePrecision] * (-N[Log[N[(N[(t$95$0 + 1.0), $MachinePrecision] / N[(1.0 - t$95$0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision])), $MachinePrecision]]]]
          
          \begin{array}{l}
          
          \\
          \begin{array}{l}
          t_0 := e^{\left(f \cdot \pi\right) \cdot -0.25}\\
          t_1 := \left(f \cdot \pi\right) \cdot 0.25\\
          \mathbf{if}\;f \leq 24:\\
          \;\;\;\;\frac{\log \left(\frac{\cosh t\_1}{\sinh t\_1}\right)}{\pi} \cdot -4\\
          
          \mathbf{else}:\\
          \;\;\;\;\frac{4}{\pi} \cdot \left(-\log \left(\frac{t\_0 + 1}{1 - t\_0}\right)\right)\\
          
          
          \end{array}
          \end{array}
          
          Derivation
          1. Split input into 2 regimes
          2. if f < 24

            1. Initial program 6.6%

              \[-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{e^{\frac{\pi}{4} \cdot f} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
            2. Taylor expanded in f around inf

              \[\leadsto \color{blue}{-4 \cdot \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)}} \]
            3. Step-by-step derivation
              1. *-commutativeN/A

                \[\leadsto \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
              2. lower-*.f64N/A

                \[\leadsto \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
            4. Applied rewrites96.9%

              \[\leadsto \color{blue}{\frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot -0.25\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot 0.25\right)}\right)}{\pi} \cdot -4} \]
            5. Applied rewrites96.9%

              \[\leadsto \color{blue}{\frac{\log \left(\frac{\cosh \left(\left(f \cdot \pi\right) \cdot 0.25\right)}{\sinh \left(\left(f \cdot \pi\right) \cdot 0.25\right)}\right)}{\pi} \cdot -4} \]

            if 24 < f

            1. Initial program 6.6%

              \[-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{e^{\frac{\pi}{4} \cdot f} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
            2. Taylor expanded in f around 0

              \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{\color{blue}{1} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
            3. Step-by-step derivation
              1. Applied rewrites5.3%

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{\color{blue}{1} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
              2. Taylor expanded in f around 0

                \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{-\frac{\pi}{4} \cdot f}}{\color{blue}{1} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
              3. Step-by-step derivation
                1. Applied rewrites6.5%

                  \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{-\frac{\pi}{4} \cdot f}}{\color{blue}{1} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
                2. Taylor expanded in f around inf

                  \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + \color{blue}{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
                3. Step-by-step derivation
                  1. distribute-lft-neg-inN/A

                    \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(\mathsf{neg}\left(\frac{1}{4}\right)\right) \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
                  2. metadata-evalN/A

                    \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\frac{-1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
                  3. lower-exp.f64N/A

                    \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\frac{-1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
                  4. *-commutativeN/A

                    \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
                  5. lower-*.f64N/A

                    \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
                  6. lower-*.f64N/A

                    \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
                  7. lift-PI.f646.5

                    \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot -0.25}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
                4. Applied rewrites6.5%

                  \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + \color{blue}{e^{\left(f \cdot \pi\right) \cdot -0.25}}}{1 - e^{-\frac{\pi}{4} \cdot f}}\right) \]
                5. Taylor expanded in f around inf

                  \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - \color{blue}{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}}\right) \]
                6. Step-by-step derivation
                  1. distribute-lft-neg-inN/A

                    \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(\mathsf{neg}\left(\frac{1}{4}\right)\right) \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}\right) \]
                  2. metadata-evalN/A

                    \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\frac{-1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}\right) \]
                  3. lower-exp.f64N/A

                    \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\frac{-1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}\right) \]
                  4. *-commutativeN/A

                    \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}\right) \]
                  5. lower-*.f64N/A

                    \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}\right) \]
                  6. lower-*.f64N/A

                    \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{-1}{4}}}\right) \]
                  7. lift-PI.f646.5

                    \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot -0.25}}{1 - e^{\left(f \cdot \pi\right) \cdot -0.25}}\right) \]
                7. Applied rewrites6.5%

                  \[\leadsto -\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot -0.25}}{1 - \color{blue}{e^{\left(f \cdot \pi\right) \cdot -0.25}}}\right) \]
                8. Step-by-step derivation
                  1. lift-neg.f64N/A

                    \[\leadsto \color{blue}{\mathsf{neg}\left(\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right)} \]
                  2. lift-*.f64N/A

                    \[\leadsto \mathsf{neg}\left(\color{blue}{\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)}\right) \]
                  3. distribute-rgt-neg-inN/A

                    \[\leadsto \color{blue}{\frac{1}{\frac{\pi}{4}} \cdot \left(\mathsf{neg}\left(\log \left(\frac{1 + e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right)\right)} \]
                9. Applied rewrites6.5%

                  \[\leadsto \color{blue}{\left(\frac{1}{\pi} \cdot 4\right) \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot -0.25} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot -0.25}}\right)\right)} \]
                10. Step-by-step derivation
                  1. lift-*.f64N/A

                    \[\leadsto \color{blue}{\left(\frac{1}{\pi} \cdot 4\right)} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
                  2. lift-PI.f64N/A

                    \[\leadsto \left(\frac{1}{\color{blue}{\mathsf{PI}\left(\right)}} \cdot 4\right) \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
                  3. lift-/.f64N/A

                    \[\leadsto \left(\color{blue}{\frac{1}{\mathsf{PI}\left(\right)}} \cdot 4\right) \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
                  4. associate-*l/N/A

                    \[\leadsto \color{blue}{\frac{1 \cdot 4}{\mathsf{PI}\left(\right)}} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
                  5. metadata-evalN/A

                    \[\leadsto \frac{\color{blue}{4}}{\mathsf{PI}\left(\right)} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
                  6. lower-/.f64N/A

                    \[\leadsto \color{blue}{\frac{4}{\mathsf{PI}\left(\right)}} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot \frac{-1}{4}}}\right)\right) \]
                  7. lift-PI.f646.5

                    \[\leadsto \frac{4}{\color{blue}{\pi}} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot -0.25} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot -0.25}}\right)\right) \]
                11. Applied rewrites6.5%

                  \[\leadsto \color{blue}{\frac{4}{\pi} \cdot \left(-\log \left(\frac{e^{\left(f \cdot \pi\right) \cdot -0.25} + 1}{1 - e^{\left(f \cdot \pi\right) \cdot -0.25}}\right)\right)} \]
              4. Recombined 2 regimes into one program.
              5. Add Preprocessing

              Alternative 4: 96.9% accurate, 1.8× speedup?

              \[\begin{array}{l} \\ \begin{array}{l} t_0 := \left(f \cdot \pi\right) \cdot 0.25\\ \frac{\log \left(\frac{\cosh t\_0}{\sinh t\_0}\right)}{\pi} \cdot -4 \end{array} \end{array} \]
              (FPCore (f)
               :precision binary64
               (let* ((t_0 (* (* f PI) 0.25)))
                 (* (/ (log (/ (cosh t_0) (sinh t_0))) PI) -4.0)))
              double code(double f) {
              	double t_0 = (f * ((double) M_PI)) * 0.25;
              	return (log((cosh(t_0) / sinh(t_0))) / ((double) M_PI)) * -4.0;
              }
              
              public static double code(double f) {
              	double t_0 = (f * Math.PI) * 0.25;
              	return (Math.log((Math.cosh(t_0) / Math.sinh(t_0))) / Math.PI) * -4.0;
              }
              
              def code(f):
              	t_0 = (f * math.pi) * 0.25
              	return (math.log((math.cosh(t_0) / math.sinh(t_0))) / math.pi) * -4.0
              
              function code(f)
              	t_0 = Float64(Float64(f * pi) * 0.25)
              	return Float64(Float64(log(Float64(cosh(t_0) / sinh(t_0))) / pi) * -4.0)
              end
              
              function tmp = code(f)
              	t_0 = (f * pi) * 0.25;
              	tmp = (log((cosh(t_0) / sinh(t_0))) / pi) * -4.0;
              end
              
              code[f_] := Block[{t$95$0 = N[(N[(f * Pi), $MachinePrecision] * 0.25), $MachinePrecision]}, N[(N[(N[Log[N[(N[Cosh[t$95$0], $MachinePrecision] / N[Sinh[t$95$0], $MachinePrecision]), $MachinePrecision]], $MachinePrecision] / Pi), $MachinePrecision] * -4.0), $MachinePrecision]]
              
              \begin{array}{l}
              
              \\
              \begin{array}{l}
              t_0 := \left(f \cdot \pi\right) \cdot 0.25\\
              \frac{\log \left(\frac{\cosh t\_0}{\sinh t\_0}\right)}{\pi} \cdot -4
              \end{array}
              \end{array}
              
              Derivation
              1. Initial program 6.6%

                \[-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{e^{\frac{\pi}{4} \cdot f} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
              2. Taylor expanded in f around inf

                \[\leadsto \color{blue}{-4 \cdot \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)}} \]
              3. Step-by-step derivation
                1. *-commutativeN/A

                  \[\leadsto \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
                2. lower-*.f64N/A

                  \[\leadsto \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
              4. Applied rewrites96.9%

                \[\leadsto \color{blue}{\frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot -0.25\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot 0.25\right)}\right)}{\pi} \cdot -4} \]
              5. Applied rewrites96.9%

                \[\leadsto \color{blue}{\frac{\log \left(\frac{\cosh \left(\left(f \cdot \pi\right) \cdot 0.25\right)}{\sinh \left(\left(f \cdot \pi\right) \cdot 0.25\right)}\right)}{\pi} \cdot -4} \]
              6. Add Preprocessing

              Alternative 5: 96.2% accurate, 2.1× speedup?

              \[\begin{array}{l} \\ \frac{\left(0.03125 \cdot \left(f \cdot f\right)\right) \cdot \left(\pi \cdot \pi\right) - \log \sinh \left(\left(f \cdot \pi\right) \cdot 0.25\right)}{\pi} \cdot -4 \end{array} \]
              (FPCore (f)
               :precision binary64
               (*
                (/ (- (* (* 0.03125 (* f f)) (* PI PI)) (log (sinh (* (* f PI) 0.25)))) PI)
                -4.0))
              double code(double f) {
              	return ((((0.03125 * (f * f)) * (((double) M_PI) * ((double) M_PI))) - log(sinh(((f * ((double) M_PI)) * 0.25)))) / ((double) M_PI)) * -4.0;
              }
              
              public static double code(double f) {
              	return ((((0.03125 * (f * f)) * (Math.PI * Math.PI)) - Math.log(Math.sinh(((f * Math.PI) * 0.25)))) / Math.PI) * -4.0;
              }
              
              def code(f):
              	return ((((0.03125 * (f * f)) * (math.pi * math.pi)) - math.log(math.sinh(((f * math.pi) * 0.25)))) / math.pi) * -4.0
              
              function code(f)
              	return Float64(Float64(Float64(Float64(Float64(0.03125 * Float64(f * f)) * Float64(pi * pi)) - log(sinh(Float64(Float64(f * pi) * 0.25)))) / pi) * -4.0)
              end
              
              function tmp = code(f)
              	tmp = ((((0.03125 * (f * f)) * (pi * pi)) - log(sinh(((f * pi) * 0.25)))) / pi) * -4.0;
              end
              
              code[f_] := N[(N[(N[(N[(N[(0.03125 * N[(f * f), $MachinePrecision]), $MachinePrecision] * N[(Pi * Pi), $MachinePrecision]), $MachinePrecision] - N[Log[N[Sinh[N[(N[(f * Pi), $MachinePrecision] * 0.25), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / Pi), $MachinePrecision] * -4.0), $MachinePrecision]
              
              \begin{array}{l}
              
              \\
              \frac{\left(0.03125 \cdot \left(f \cdot f\right)\right) \cdot \left(\pi \cdot \pi\right) - \log \sinh \left(\left(f \cdot \pi\right) \cdot 0.25\right)}{\pi} \cdot -4
              \end{array}
              
              Derivation
              1. Initial program 6.6%

                \[-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{e^{\frac{\pi}{4} \cdot f} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
              2. Taylor expanded in f around inf

                \[\leadsto \color{blue}{-4 \cdot \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)}} \]
              3. Step-by-step derivation
                1. *-commutativeN/A

                  \[\leadsto \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
                2. lower-*.f64N/A

                  \[\leadsto \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
              4. Applied rewrites96.9%

                \[\leadsto \color{blue}{\frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot -0.25\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot 0.25\right)}\right)}{\pi} \cdot -4} \]
              5. Step-by-step derivation
                1. lift-log.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
                2. lift-/.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
                3. lift-*.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
                4. lift-cosh.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
                5. lift-*.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
                6. lift-PI.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
                7. lift-*.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
                8. lift-*.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
                9. lift-sinh.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
                10. lift-*.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
                11. lift-PI.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
                12. lift-*.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2 \cdot \sinh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
                13. associate-/r*N/A

                  \[\leadsto \frac{\log \left(\frac{\frac{2 \cdot \cosh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{-1}{4}\right)}{2}}{\sinh \left(\left(\mathsf{PI}\left(\right) \cdot f\right) \cdot \frac{1}{4}\right)}\right)}{\pi} \cdot -4 \]
              6. Applied rewrites96.9%

                \[\leadsto \frac{\log \cosh \left(\left(f \cdot \pi\right) \cdot 0.25\right) - \log \sinh \left(\left(f \cdot \pi\right) \cdot 0.25\right)}{\pi} \cdot -4 \]
              7. Taylor expanded in f around 0

                \[\leadsto \frac{\frac{1}{32} \cdot \left({f}^{2} \cdot {\mathsf{PI}\left(\right)}^{2}\right) - \log \sinh \left(\left(f \cdot \pi\right) \cdot \frac{1}{4}\right)}{\pi} \cdot -4 \]
              8. Step-by-step derivation
                1. associate-*r*N/A

                  \[\leadsto \frac{\left(\frac{1}{32} \cdot {f}^{2}\right) \cdot {\mathsf{PI}\left(\right)}^{2} - \log \sinh \left(\left(f \cdot \pi\right) \cdot \frac{1}{4}\right)}{\pi} \cdot -4 \]
                2. lower-*.f64N/A

                  \[\leadsto \frac{\left(\frac{1}{32} \cdot {f}^{2}\right) \cdot {\mathsf{PI}\left(\right)}^{2} - \log \sinh \left(\left(f \cdot \pi\right) \cdot \frac{1}{4}\right)}{\pi} \cdot -4 \]
                3. lower-*.f64N/A

                  \[\leadsto \frac{\left(\frac{1}{32} \cdot {f}^{2}\right) \cdot {\mathsf{PI}\left(\right)}^{2} - \log \sinh \left(\left(f \cdot \pi\right) \cdot \frac{1}{4}\right)}{\pi} \cdot -4 \]
                4. unpow2N/A

                  \[\leadsto \frac{\left(\frac{1}{32} \cdot \left(f \cdot f\right)\right) \cdot {\mathsf{PI}\left(\right)}^{2} - \log \sinh \left(\left(f \cdot \pi\right) \cdot \frac{1}{4}\right)}{\pi} \cdot -4 \]
                5. lower-*.f64N/A

                  \[\leadsto \frac{\left(\frac{1}{32} \cdot \left(f \cdot f\right)\right) \cdot {\mathsf{PI}\left(\right)}^{2} - \log \sinh \left(\left(f \cdot \pi\right) \cdot \frac{1}{4}\right)}{\pi} \cdot -4 \]
                6. unpow2N/A

                  \[\leadsto \frac{\left(\frac{1}{32} \cdot \left(f \cdot f\right)\right) \cdot \left(\mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)\right) - \log \sinh \left(\left(f \cdot \pi\right) \cdot \frac{1}{4}\right)}{\pi} \cdot -4 \]
                7. lower-*.f64N/A

                  \[\leadsto \frac{\left(\frac{1}{32} \cdot \left(f \cdot f\right)\right) \cdot \left(\mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)\right) - \log \sinh \left(\left(f \cdot \pi\right) \cdot \frac{1}{4}\right)}{\pi} \cdot -4 \]
                8. lift-PI.f64N/A

                  \[\leadsto \frac{\left(\frac{1}{32} \cdot \left(f \cdot f\right)\right) \cdot \left(\pi \cdot \mathsf{PI}\left(\right)\right) - \log \sinh \left(\left(f \cdot \pi\right) \cdot \frac{1}{4}\right)}{\pi} \cdot -4 \]
                9. lift-PI.f6496.2

                  \[\leadsto \frac{\left(0.03125 \cdot \left(f \cdot f\right)\right) \cdot \left(\pi \cdot \pi\right) - \log \sinh \left(\left(f \cdot \pi\right) \cdot 0.25\right)}{\pi} \cdot -4 \]
              9. Applied rewrites96.2%

                \[\leadsto \frac{\left(0.03125 \cdot \left(f \cdot f\right)\right) \cdot \left(\pi \cdot \pi\right) - \log \sinh \left(\left(f \cdot \pi\right) \cdot 0.25\right)}{\pi} \cdot -4 \]
              10. Add Preprocessing

              Alternative 6: 95.8% accurate, 2.2× speedup?

              \[\begin{array}{l} \\ \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot -0.25\right)}{\left(0.5 \cdot \pi\right) \cdot f}\right)}{\pi} \cdot -4 \end{array} \]
              (FPCore (f)
               :precision binary64
               (* (/ (log (/ (* 2.0 (cosh (* (* PI f) -0.25))) (* (* 0.5 PI) f))) PI) -4.0))
              double code(double f) {
              	return (log(((2.0 * cosh(((((double) M_PI) * f) * -0.25))) / ((0.5 * ((double) M_PI)) * f))) / ((double) M_PI)) * -4.0;
              }
              
              public static double code(double f) {
              	return (Math.log(((2.0 * Math.cosh(((Math.PI * f) * -0.25))) / ((0.5 * Math.PI) * f))) / Math.PI) * -4.0;
              }
              
              def code(f):
              	return (math.log(((2.0 * math.cosh(((math.pi * f) * -0.25))) / ((0.5 * math.pi) * f))) / math.pi) * -4.0
              
              function code(f)
              	return Float64(Float64(log(Float64(Float64(2.0 * cosh(Float64(Float64(pi * f) * -0.25))) / Float64(Float64(0.5 * pi) * f))) / pi) * -4.0)
              end
              
              function tmp = code(f)
              	tmp = (log(((2.0 * cosh(((pi * f) * -0.25))) / ((0.5 * pi) * f))) / pi) * -4.0;
              end
              
              code[f_] := N[(N[(N[Log[N[(N[(2.0 * N[Cosh[N[(N[(Pi * f), $MachinePrecision] * -0.25), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(N[(0.5 * Pi), $MachinePrecision] * f), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] / Pi), $MachinePrecision] * -4.0), $MachinePrecision]
              
              \begin{array}{l}
              
              \\
              \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot -0.25\right)}{\left(0.5 \cdot \pi\right) \cdot f}\right)}{\pi} \cdot -4
              \end{array}
              
              Derivation
              1. Initial program 6.6%

                \[-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{e^{\frac{\pi}{4} \cdot f} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
              2. Taylor expanded in f around inf

                \[\leadsto \color{blue}{-4 \cdot \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)}} \]
              3. Step-by-step derivation
                1. *-commutativeN/A

                  \[\leadsto \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
                2. lower-*.f64N/A

                  \[\leadsto \frac{\log \left(\frac{e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)} + e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)}}{e^{\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)} - e^{\mathsf{neg}\left(\frac{1}{4} \cdot \left(f \cdot \mathsf{PI}\left(\right)\right)\right)}}\right)}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
              4. Applied rewrites96.9%

                \[\leadsto \color{blue}{\frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot -0.25\right)}{2 \cdot \sinh \left(\left(\pi \cdot f\right) \cdot 0.25\right)}\right)}{\pi} \cdot -4} \]
              5. Taylor expanded in f around 0

                \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{f \cdot \left(\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)\right)}\right)}{\pi} \cdot -4 \]
              6. Step-by-step derivation
                1. *-commutativeN/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{\left(\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)\right) \cdot f}\right)}{\pi} \cdot -4 \]
                2. lower-*.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{\left(\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)\right) \cdot f}\right)}{\pi} \cdot -4 \]
                3. distribute-rgt-out--N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{\left(\mathsf{PI}\left(\right) \cdot \left(\frac{1}{4} - \frac{-1}{4}\right)\right) \cdot f}\right)}{\pi} \cdot -4 \]
                4. metadata-evalN/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{\left(\mathsf{PI}\left(\right) \cdot \frac{1}{2}\right) \cdot f}\right)}{\pi} \cdot -4 \]
                5. *-commutativeN/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{\left(\frac{1}{2} \cdot \mathsf{PI}\left(\right)\right) \cdot f}\right)}{\pi} \cdot -4 \]
                6. lower-*.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot \frac{-1}{4}\right)}{\left(\frac{1}{2} \cdot \mathsf{PI}\left(\right)\right) \cdot f}\right)}{\pi} \cdot -4 \]
                7. lift-PI.f6495.8

                  \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot -0.25\right)}{\left(0.5 \cdot \pi\right) \cdot f}\right)}{\pi} \cdot -4 \]
              7. Applied rewrites95.8%

                \[\leadsto \frac{\log \left(\frac{2 \cdot \cosh \left(\left(\pi \cdot f\right) \cdot -0.25\right)}{\left(0.5 \cdot \pi\right) \cdot f}\right)}{\pi} \cdot -4 \]
              8. Add Preprocessing

              Alternative 7: 95.8% accurate, 3.4× speedup?

              \[\begin{array}{l} \\ \frac{\log 2 - \log \left(\left(0.5 \cdot \pi\right) \cdot f\right)}{\pi} \cdot -4 \end{array} \]
              (FPCore (f)
               :precision binary64
               (* (/ (- (log 2.0) (log (* (* 0.5 PI) f))) PI) -4.0))
              double code(double f) {
              	return ((log(2.0) - log(((0.5 * ((double) M_PI)) * f))) / ((double) M_PI)) * -4.0;
              }
              
              public static double code(double f) {
              	return ((Math.log(2.0) - Math.log(((0.5 * Math.PI) * f))) / Math.PI) * -4.0;
              }
              
              def code(f):
              	return ((math.log(2.0) - math.log(((0.5 * math.pi) * f))) / math.pi) * -4.0
              
              function code(f)
              	return Float64(Float64(Float64(log(2.0) - log(Float64(Float64(0.5 * pi) * f))) / pi) * -4.0)
              end
              
              function tmp = code(f)
              	tmp = ((log(2.0) - log(((0.5 * pi) * f))) / pi) * -4.0;
              end
              
              code[f_] := N[(N[(N[(N[Log[2.0], $MachinePrecision] - N[Log[N[(N[(0.5 * Pi), $MachinePrecision] * f), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / Pi), $MachinePrecision] * -4.0), $MachinePrecision]
              
              \begin{array}{l}
              
              \\
              \frac{\log 2 - \log \left(\left(0.5 \cdot \pi\right) \cdot f\right)}{\pi} \cdot -4
              \end{array}
              
              Derivation
              1. Initial program 6.6%

                \[-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{e^{\frac{\pi}{4} \cdot f} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
              2. Taylor expanded in f around 0

                \[\leadsto \color{blue}{-4 \cdot \frac{\log \left(\frac{2}{\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)}\right) + -1 \cdot \log f}{\mathsf{PI}\left(\right)}} \]
              3. Step-by-step derivation
                1. *-commutativeN/A

                  \[\leadsto \frac{\log \left(\frac{2}{\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)}\right) + -1 \cdot \log f}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
                2. lower-*.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2}{\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)}\right) + -1 \cdot \log f}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
              4. Applied rewrites95.8%

                \[\leadsto \color{blue}{\frac{\log \left(\frac{2}{\left(\pi \cdot 0.5\right) \cdot f}\right)}{\pi} \cdot -4} \]
              5. Step-by-step derivation
                1. lift-log.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2}{\left(\pi \cdot \frac{1}{2}\right) \cdot f}\right)}{\pi} \cdot -4 \]
                2. lift-/.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2}{\left(\pi \cdot \frac{1}{2}\right) \cdot f}\right)}{\pi} \cdot -4 \]
                3. log-divN/A

                  \[\leadsto \frac{\log 2 - \log \left(\left(\pi \cdot \frac{1}{2}\right) \cdot f\right)}{\pi} \cdot -4 \]
                4. lift-*.f64N/A

                  \[\leadsto \frac{\log 2 - \log \left(\left(\pi \cdot \frac{1}{2}\right) \cdot f\right)}{\pi} \cdot -4 \]
                5. lift-PI.f64N/A

                  \[\leadsto \frac{\log 2 - \log \left(\left(\mathsf{PI}\left(\right) \cdot \frac{1}{2}\right) \cdot f\right)}{\pi} \cdot -4 \]
                6. lift-*.f64N/A

                  \[\leadsto \frac{\log 2 - \log \left(\left(\mathsf{PI}\left(\right) \cdot \frac{1}{2}\right) \cdot f\right)}{\pi} \cdot -4 \]
                7. metadata-evalN/A

                  \[\leadsto \frac{\log 2 - \log \left(\left(\mathsf{PI}\left(\right) \cdot \left(\frac{1}{4} - \frac{-1}{4}\right)\right) \cdot f\right)}{\pi} \cdot -4 \]
                8. distribute-rgt-out--N/A

                  \[\leadsto \frac{\log 2 - \log \left(\left(\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)\right) \cdot f\right)}{\pi} \cdot -4 \]
                9. *-commutativeN/A

                  \[\leadsto \frac{\log 2 - \log \left(f \cdot \left(\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)\right)\right)}{\pi} \cdot -4 \]
                10. sum-logN/A

                  \[\leadsto \frac{\log 2 - \left(\log f + \log \left(\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)\right)\right)}{\pi} \cdot -4 \]
                11. lower--.f64N/A

                  \[\leadsto \frac{\log 2 - \left(\log f + \log \left(\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)\right)\right)}{\pi} \cdot -4 \]
                12. lower-log.f64N/A

                  \[\leadsto \frac{\log 2 - \left(\log f + \log \left(\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)\right)\right)}{\pi} \cdot -4 \]
                13. sum-logN/A

                  \[\leadsto \frac{\log 2 - \log \left(f \cdot \left(\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)\right)\right)}{\pi} \cdot -4 \]
                14. lower-log.f64N/A

                  \[\leadsto \frac{\log 2 - \log \left(f \cdot \left(\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)\right)\right)}{\pi} \cdot -4 \]
                15. *-commutativeN/A

                  \[\leadsto \frac{\log 2 - \log \left(\left(\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)\right) \cdot f\right)}{\pi} \cdot -4 \]
                16. lower-*.f64N/A

                  \[\leadsto \frac{\log 2 - \log \left(\left(\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)\right) \cdot f\right)}{\pi} \cdot -4 \]
              6. Applied rewrites95.8%

                \[\leadsto \frac{\log 2 - \log \left(\left(0.5 \cdot \pi\right) \cdot f\right)}{\pi} \cdot -4 \]
              7. Add Preprocessing

              Alternative 8: 95.8% accurate, 4.8× speedup?

              \[\begin{array}{l} \\ \frac{\log \left(\frac{4}{f \cdot \pi}\right)}{\pi} \cdot -4 \end{array} \]
              (FPCore (f) :precision binary64 (* (/ (log (/ 4.0 (* f PI))) PI) -4.0))
              double code(double f) {
              	return (log((4.0 / (f * ((double) M_PI)))) / ((double) M_PI)) * -4.0;
              }
              
              public static double code(double f) {
              	return (Math.log((4.0 / (f * Math.PI))) / Math.PI) * -4.0;
              }
              
              def code(f):
              	return (math.log((4.0 / (f * math.pi))) / math.pi) * -4.0
              
              function code(f)
              	return Float64(Float64(log(Float64(4.0 / Float64(f * pi))) / pi) * -4.0)
              end
              
              function tmp = code(f)
              	tmp = (log((4.0 / (f * pi))) / pi) * -4.0;
              end
              
              code[f_] := N[(N[(N[Log[N[(4.0 / N[(f * Pi), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] / Pi), $MachinePrecision] * -4.0), $MachinePrecision]
              
              \begin{array}{l}
              
              \\
              \frac{\log \left(\frac{4}{f \cdot \pi}\right)}{\pi} \cdot -4
              \end{array}
              
              Derivation
              1. Initial program 6.6%

                \[-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{e^{\frac{\pi}{4} \cdot f} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right) \]
              2. Taylor expanded in f around 0

                \[\leadsto \color{blue}{-4 \cdot \frac{\log \left(\frac{2}{\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)}\right) + -1 \cdot \log f}{\mathsf{PI}\left(\right)}} \]
              3. Step-by-step derivation
                1. *-commutativeN/A

                  \[\leadsto \frac{\log \left(\frac{2}{\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)}\right) + -1 \cdot \log f}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
                2. lower-*.f64N/A

                  \[\leadsto \frac{\log \left(\frac{2}{\frac{1}{4} \cdot \mathsf{PI}\left(\right) - \frac{-1}{4} \cdot \mathsf{PI}\left(\right)}\right) + -1 \cdot \log f}{\mathsf{PI}\left(\right)} \cdot \color{blue}{-4} \]
              4. Applied rewrites95.8%

                \[\leadsto \color{blue}{\frac{\log \left(\frac{2}{\left(\pi \cdot 0.5\right) \cdot f}\right)}{\pi} \cdot -4} \]
              5. Taylor expanded in f around 0

                \[\leadsto \frac{\log \left(\frac{4}{f \cdot \mathsf{PI}\left(\right)}\right)}{\pi} \cdot -4 \]
              6. Step-by-step derivation
                1. lower-/.f64N/A

                  \[\leadsto \frac{\log \left(\frac{4}{f \cdot \mathsf{PI}\left(\right)}\right)}{\pi} \cdot -4 \]
                2. lower-*.f64N/A

                  \[\leadsto \frac{\log \left(\frac{4}{f \cdot \mathsf{PI}\left(\right)}\right)}{\pi} \cdot -4 \]
                3. lift-PI.f6495.8

                  \[\leadsto \frac{\log \left(\frac{4}{f \cdot \pi}\right)}{\pi} \cdot -4 \]
              7. Applied rewrites95.8%

                \[\leadsto \frac{\log \left(\frac{4}{f \cdot \pi}\right)}{\pi} \cdot -4 \]
              8. Add Preprocessing

              Reproduce

              ?
              herbie shell --seed 2025131 
              (FPCore (f)
                :name "VandenBroeck and Keller, Equation (20)"
                :precision binary64
                (- (* (/ 1.0 (/ PI 4.0)) (log (/ (+ (exp (* (/ PI 4.0) f)) (exp (- (* (/ PI 4.0) f)))) (- (exp (* (/ PI 4.0) f)) (exp (- (* (/ PI 4.0) f)))))))))