VandenBroeck and Keller, Equation (6)

Percentage Accurate: 76.1% → 98.3%
Time: 16.3s
Alternatives: 8
Speedup: 3.7×

Specification

?
\[\begin{array}{l} \\ \pi \cdot \ell - \frac{1}{F \cdot F} \cdot \tan \left(\pi \cdot \ell\right) \end{array} \]
(FPCore (F l)
 :precision binary64
 (- (* PI l) (* (/ 1.0 (* F F)) (tan (* PI l)))))
double code(double F, double l) {
	return (((double) M_PI) * l) - ((1.0 / (F * F)) * tan((((double) M_PI) * l)));
}
public static double code(double F, double l) {
	return (Math.PI * l) - ((1.0 / (F * F)) * Math.tan((Math.PI * l)));
}
def code(F, l):
	return (math.pi * l) - ((1.0 / (F * F)) * math.tan((math.pi * l)))
function code(F, l)
	return Float64(Float64(pi * l) - Float64(Float64(1.0 / Float64(F * F)) * tan(Float64(pi * l))))
end
function tmp = code(F, l)
	tmp = (pi * l) - ((1.0 / (F * F)) * tan((pi * l)));
end
code[F_, l_] := N[(N[(Pi * l), $MachinePrecision] - N[(N[(1.0 / N[(F * F), $MachinePrecision]), $MachinePrecision] * N[Tan[N[(Pi * l), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\pi \cdot \ell - \frac{1}{F \cdot F} \cdot \tan \left(\pi \cdot \ell\right)
\end{array}

Sampling outcomes in binary64 precision:

Local Percentage Accuracy vs ?

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

Accuracy vs Speed?

Herbie found 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: 76.1% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \pi \cdot \ell - \frac{1}{F \cdot F} \cdot \tan \left(\pi \cdot \ell\right) \end{array} \]
(FPCore (F l)
 :precision binary64
 (- (* PI l) (* (/ 1.0 (* F F)) (tan (* PI l)))))
double code(double F, double l) {
	return (((double) M_PI) * l) - ((1.0 / (F * F)) * tan((((double) M_PI) * l)));
}
public static double code(double F, double l) {
	return (Math.PI * l) - ((1.0 / (F * F)) * Math.tan((Math.PI * l)));
}
def code(F, l):
	return (math.pi * l) - ((1.0 / (F * F)) * math.tan((math.pi * l)))
function code(F, l)
	return Float64(Float64(pi * l) - Float64(Float64(1.0 / Float64(F * F)) * tan(Float64(pi * l))))
end
function tmp = code(F, l)
	tmp = (pi * l) - ((1.0 / (F * F)) * tan((pi * l)));
end
code[F_, l_] := N[(N[(Pi * l), $MachinePrecision] - N[(N[(1.0 / N[(F * F), $MachinePrecision]), $MachinePrecision] * N[Tan[N[(Pi * l), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\pi \cdot \ell - \frac{1}{F \cdot F} \cdot \tan \left(\pi \cdot \ell\right)
\end{array}

Alternative 1: 98.3% accurate, 2.0× speedup?

\[\begin{array}{l} l\_m = \left|\ell\right| \\ l\_s = \mathsf{copysign}\left(1, \ell\right) \\ l\_s \cdot \begin{array}{l} \mathbf{if}\;\pi \cdot l\_m \leq 4000000000000:\\ \;\;\;\;\mathsf{fma}\left(\frac{\pi \cdot l\_m}{F}, \frac{-1}{F}, \pi \cdot l\_m\right)\\ \mathbf{else}:\\ \;\;\;\;\left(l\_m \cdot \sqrt{\sqrt{\pi}}\right) \cdot \sqrt{\pi \cdot \sqrt{\pi}}\\ \end{array} \end{array} \]
l\_m = (fabs.f64 l)
l\_s = (copysign.f64 #s(literal 1 binary64) l)
(FPCore (l_s F l_m)
 :precision binary64
 (*
  l_s
  (if (<= (* PI l_m) 4000000000000.0)
    (fma (/ (* PI l_m) F) (/ -1.0 F) (* PI l_m))
    (* (* l_m (sqrt (sqrt PI))) (sqrt (* PI (sqrt PI)))))))
l\_m = fabs(l);
l\_s = copysign(1.0, l);
double code(double l_s, double F, double l_m) {
	double tmp;
	if ((((double) M_PI) * l_m) <= 4000000000000.0) {
		tmp = fma(((((double) M_PI) * l_m) / F), (-1.0 / F), (((double) M_PI) * l_m));
	} else {
		tmp = (l_m * sqrt(sqrt(((double) M_PI)))) * sqrt((((double) M_PI) * sqrt(((double) M_PI))));
	}
	return l_s * tmp;
}
l\_m = abs(l)
l\_s = copysign(1.0, l)
function code(l_s, F, l_m)
	tmp = 0.0
	if (Float64(pi * l_m) <= 4000000000000.0)
		tmp = fma(Float64(Float64(pi * l_m) / F), Float64(-1.0 / F), Float64(pi * l_m));
	else
		tmp = Float64(Float64(l_m * sqrt(sqrt(pi))) * sqrt(Float64(pi * sqrt(pi))));
	end
	return Float64(l_s * tmp)
end
l\_m = N[Abs[l], $MachinePrecision]
l\_s = N[With[{TMP1 = Abs[1.0], TMP2 = Sign[l]}, TMP1 * If[TMP2 == 0, 1, TMP2]], $MachinePrecision]
code[l$95$s_, F_, l$95$m_] := N[(l$95$s * If[LessEqual[N[(Pi * l$95$m), $MachinePrecision], 4000000000000.0], N[(N[(N[(Pi * l$95$m), $MachinePrecision] / F), $MachinePrecision] * N[(-1.0 / F), $MachinePrecision] + N[(Pi * l$95$m), $MachinePrecision]), $MachinePrecision], N[(N[(l$95$m * N[Sqrt[N[Sqrt[Pi], $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * N[Sqrt[N[(Pi * N[Sqrt[Pi], $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]]), $MachinePrecision]
\begin{array}{l}
l\_m = \left|\ell\right|
\\
l\_s = \mathsf{copysign}\left(1, \ell\right)

\\
l\_s \cdot \begin{array}{l}
\mathbf{if}\;\pi \cdot l\_m \leq 4000000000000:\\
\;\;\;\;\mathsf{fma}\left(\frac{\pi \cdot l\_m}{F}, \frac{-1}{F}, \pi \cdot l\_m\right)\\

\mathbf{else}:\\
\;\;\;\;\left(l\_m \cdot \sqrt{\sqrt{\pi}}\right) \cdot \sqrt{\pi \cdot \sqrt{\pi}}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (*.f64 (PI.f64) l) < 4e12

    1. Initial program 90.3%

      \[\pi \cdot \ell - \frac{1}{F \cdot F} \cdot \tan \left(\pi \cdot \ell\right) \]
    2. Add Preprocessing
    3. Step-by-step derivation
      1. lift--.f64N/A

        \[\leadsto \color{blue}{\mathsf{PI}\left(\right) \cdot \ell - \frac{1}{F \cdot F} \cdot \tan \left(\mathsf{PI}\left(\right) \cdot \ell\right)} \]
      2. sub-negN/A

        \[\leadsto \color{blue}{\mathsf{PI}\left(\right) \cdot \ell + \left(\mathsf{neg}\left(\frac{1}{F \cdot F} \cdot \tan \left(\mathsf{PI}\left(\right) \cdot \ell\right)\right)\right)} \]
      3. +-commutativeN/A

        \[\leadsto \color{blue}{\left(\mathsf{neg}\left(\frac{1}{F \cdot F} \cdot \tan \left(\mathsf{PI}\left(\right) \cdot \ell\right)\right)\right) + \mathsf{PI}\left(\right) \cdot \ell} \]
      4. lift-*.f64N/A

        \[\leadsto \left(\mathsf{neg}\left(\color{blue}{\frac{1}{F \cdot F} \cdot \tan \left(\mathsf{PI}\left(\right) \cdot \ell\right)}\right)\right) + \mathsf{PI}\left(\right) \cdot \ell \]
      5. *-commutativeN/A

        \[\leadsto \left(\mathsf{neg}\left(\color{blue}{\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right) \cdot \frac{1}{F \cdot F}}\right)\right) + \mathsf{PI}\left(\right) \cdot \ell \]
      6. lift-/.f64N/A

        \[\leadsto \left(\mathsf{neg}\left(\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right) \cdot \color{blue}{\frac{1}{F \cdot F}}\right)\right) + \mathsf{PI}\left(\right) \cdot \ell \]
      7. un-div-invN/A

        \[\leadsto \left(\mathsf{neg}\left(\color{blue}{\frac{\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right)}{F \cdot F}}\right)\right) + \mathsf{PI}\left(\right) \cdot \ell \]
      8. distribute-neg-frac2N/A

        \[\leadsto \color{blue}{\frac{\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right)}{\mathsf{neg}\left(F \cdot F\right)}} + \mathsf{PI}\left(\right) \cdot \ell \]
      9. *-rgt-identityN/A

        \[\leadsto \frac{\color{blue}{\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right) \cdot 1}}{\mathsf{neg}\left(F \cdot F\right)} + \mathsf{PI}\left(\right) \cdot \ell \]
      10. lift-*.f64N/A

        \[\leadsto \frac{\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right) \cdot 1}{\mathsf{neg}\left(\color{blue}{F \cdot F}\right)} + \mathsf{PI}\left(\right) \cdot \ell \]
      11. distribute-rgt-neg-inN/A

        \[\leadsto \frac{\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right) \cdot 1}{\color{blue}{F \cdot \left(\mathsf{neg}\left(F\right)\right)}} + \mathsf{PI}\left(\right) \cdot \ell \]
      12. times-fracN/A

        \[\leadsto \color{blue}{\frac{\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right)}{F} \cdot \frac{1}{\mathsf{neg}\left(F\right)}} + \mathsf{PI}\left(\right) \cdot \ell \]
      13. distribute-neg-frac2N/A

        \[\leadsto \frac{\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right)}{F} \cdot \color{blue}{\left(\mathsf{neg}\left(\frac{1}{F}\right)\right)} + \mathsf{PI}\left(\right) \cdot \ell \]
      14. lower-fma.f64N/A

        \[\leadsto \color{blue}{\mathsf{fma}\left(\frac{\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right)}{F}, \mathsf{neg}\left(\frac{1}{F}\right), \mathsf{PI}\left(\right) \cdot \ell\right)} \]
    4. Applied rewrites99.6%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\frac{\tan \left(\pi \cdot \ell\right)}{F}, \frac{-1}{F}, \pi \cdot \ell\right)} \]
    5. Taylor expanded in l around 0

      \[\leadsto \mathsf{fma}\left(\frac{\color{blue}{\ell \cdot \mathsf{PI}\left(\right)}}{F}, \frac{-1}{F}, \mathsf{PI}\left(\right) \cdot \ell\right) \]
    6. Step-by-step derivation
      1. lower-*.f64N/A

        \[\leadsto \mathsf{fma}\left(\frac{\color{blue}{\ell \cdot \mathsf{PI}\left(\right)}}{F}, \frac{-1}{F}, \mathsf{PI}\left(\right) \cdot \ell\right) \]
      2. lower-PI.f6499.6

        \[\leadsto \mathsf{fma}\left(\frac{\ell \cdot \color{blue}{\pi}}{F}, \frac{-1}{F}, \pi \cdot \ell\right) \]
    7. Applied rewrites99.6%

      \[\leadsto \mathsf{fma}\left(\frac{\color{blue}{\ell \cdot \pi}}{F}, \frac{-1}{F}, \pi \cdot \ell\right) \]

    if 4e12 < (*.f64 (PI.f64) l)

    1. Initial program 68.7%

      \[\pi \cdot \ell - \frac{1}{F \cdot F} \cdot \tan \left(\pi \cdot \ell\right) \]
    2. Add Preprocessing
    3. Taylor expanded in l around inf

      \[\leadsto \color{blue}{\ell \cdot \mathsf{PI}\left(\right)} \]
    4. Step-by-step derivation
      1. lower-*.f64N/A

        \[\leadsto \color{blue}{\ell \cdot \mathsf{PI}\left(\right)} \]
      2. lower-PI.f6499.6

        \[\leadsto \ell \cdot \color{blue}{\pi} \]
    5. Applied rewrites99.6%

      \[\leadsto \color{blue}{\ell \cdot \pi} \]
    6. Step-by-step derivation
      1. Applied rewrites99.7%

        \[\leadsto \left(\ell \cdot \sqrt{\sqrt{\pi}}\right) \cdot \color{blue}{\sqrt{\pi \cdot \sqrt{\pi}}} \]
    7. Recombined 2 regimes into one program.
    8. Final simplification99.6%

      \[\leadsto \begin{array}{l} \mathbf{if}\;\pi \cdot \ell \leq 4000000000000:\\ \;\;\;\;\mathsf{fma}\left(\frac{\pi \cdot \ell}{F}, \frac{-1}{F}, \pi \cdot \ell\right)\\ \mathbf{else}:\\ \;\;\;\;\left(\ell \cdot \sqrt{\sqrt{\pi}}\right) \cdot \sqrt{\pi \cdot \sqrt{\pi}}\\ \end{array} \]
    9. Add Preprocessing

    Alternative 2: 83.7% accurate, 0.4× speedup?

    \[\begin{array}{l} l\_m = \left|\ell\right| \\ l\_s = \mathsf{copysign}\left(1, \ell\right) \\ \begin{array}{l} t_0 := \pi \cdot l\_m + \tan \left(\pi \cdot l\_m\right) \cdot \frac{-1}{F \cdot F}\\ l\_s \cdot \begin{array}{l} \mathbf{if}\;t\_0 \leq -5 \cdot 10^{+189}:\\ \;\;\;\;\pi \cdot l\_m\\ \mathbf{elif}\;t\_0 \leq -2 \cdot 10^{-283}:\\ \;\;\;\;\frac{\pi \cdot l\_m}{F \cdot \left(-F\right)}\\ \mathbf{else}:\\ \;\;\;\;\pi \cdot l\_m\\ \end{array} \end{array} \end{array} \]
    l\_m = (fabs.f64 l)
    l\_s = (copysign.f64 #s(literal 1 binary64) l)
    (FPCore (l_s F l_m)
     :precision binary64
     (let* ((t_0 (+ (* PI l_m) (* (tan (* PI l_m)) (/ -1.0 (* F F))))))
       (*
        l_s
        (if (<= t_0 -5e+189)
          (* PI l_m)
          (if (<= t_0 -2e-283) (/ (* PI l_m) (* F (- F))) (* PI l_m))))))
    l\_m = fabs(l);
    l\_s = copysign(1.0, l);
    double code(double l_s, double F, double l_m) {
    	double t_0 = (((double) M_PI) * l_m) + (tan((((double) M_PI) * l_m)) * (-1.0 / (F * F)));
    	double tmp;
    	if (t_0 <= -5e+189) {
    		tmp = ((double) M_PI) * l_m;
    	} else if (t_0 <= -2e-283) {
    		tmp = (((double) M_PI) * l_m) / (F * -F);
    	} else {
    		tmp = ((double) M_PI) * l_m;
    	}
    	return l_s * tmp;
    }
    
    l\_m = Math.abs(l);
    l\_s = Math.copySign(1.0, l);
    public static double code(double l_s, double F, double l_m) {
    	double t_0 = (Math.PI * l_m) + (Math.tan((Math.PI * l_m)) * (-1.0 / (F * F)));
    	double tmp;
    	if (t_0 <= -5e+189) {
    		tmp = Math.PI * l_m;
    	} else if (t_0 <= -2e-283) {
    		tmp = (Math.PI * l_m) / (F * -F);
    	} else {
    		tmp = Math.PI * l_m;
    	}
    	return l_s * tmp;
    }
    
    l\_m = math.fabs(l)
    l\_s = math.copysign(1.0, l)
    def code(l_s, F, l_m):
    	t_0 = (math.pi * l_m) + (math.tan((math.pi * l_m)) * (-1.0 / (F * F)))
    	tmp = 0
    	if t_0 <= -5e+189:
    		tmp = math.pi * l_m
    	elif t_0 <= -2e-283:
    		tmp = (math.pi * l_m) / (F * -F)
    	else:
    		tmp = math.pi * l_m
    	return l_s * tmp
    
    l\_m = abs(l)
    l\_s = copysign(1.0, l)
    function code(l_s, F, l_m)
    	t_0 = Float64(Float64(pi * l_m) + Float64(tan(Float64(pi * l_m)) * Float64(-1.0 / Float64(F * F))))
    	tmp = 0.0
    	if (t_0 <= -5e+189)
    		tmp = Float64(pi * l_m);
    	elseif (t_0 <= -2e-283)
    		tmp = Float64(Float64(pi * l_m) / Float64(F * Float64(-F)));
    	else
    		tmp = Float64(pi * l_m);
    	end
    	return Float64(l_s * tmp)
    end
    
    l\_m = abs(l);
    l\_s = sign(l) * abs(1.0);
    function tmp_2 = code(l_s, F, l_m)
    	t_0 = (pi * l_m) + (tan((pi * l_m)) * (-1.0 / (F * F)));
    	tmp = 0.0;
    	if (t_0 <= -5e+189)
    		tmp = pi * l_m;
    	elseif (t_0 <= -2e-283)
    		tmp = (pi * l_m) / (F * -F);
    	else
    		tmp = pi * l_m;
    	end
    	tmp_2 = l_s * tmp;
    end
    
    l\_m = N[Abs[l], $MachinePrecision]
    l\_s = N[With[{TMP1 = Abs[1.0], TMP2 = Sign[l]}, TMP1 * If[TMP2 == 0, 1, TMP2]], $MachinePrecision]
    code[l$95$s_, F_, l$95$m_] := Block[{t$95$0 = N[(N[(Pi * l$95$m), $MachinePrecision] + N[(N[Tan[N[(Pi * l$95$m), $MachinePrecision]], $MachinePrecision] * N[(-1.0 / N[(F * F), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]}, N[(l$95$s * If[LessEqual[t$95$0, -5e+189], N[(Pi * l$95$m), $MachinePrecision], If[LessEqual[t$95$0, -2e-283], N[(N[(Pi * l$95$m), $MachinePrecision] / N[(F * (-F)), $MachinePrecision]), $MachinePrecision], N[(Pi * l$95$m), $MachinePrecision]]]), $MachinePrecision]]
    
    \begin{array}{l}
    l\_m = \left|\ell\right|
    \\
    l\_s = \mathsf{copysign}\left(1, \ell\right)
    
    \\
    \begin{array}{l}
    t_0 := \pi \cdot l\_m + \tan \left(\pi \cdot l\_m\right) \cdot \frac{-1}{F \cdot F}\\
    l\_s \cdot \begin{array}{l}
    \mathbf{if}\;t\_0 \leq -5 \cdot 10^{+189}:\\
    \;\;\;\;\pi \cdot l\_m\\
    
    \mathbf{elif}\;t\_0 \leq -2 \cdot 10^{-283}:\\
    \;\;\;\;\frac{\pi \cdot l\_m}{F \cdot \left(-F\right)}\\
    
    \mathbf{else}:\\
    \;\;\;\;\pi \cdot l\_m\\
    
    
    \end{array}
    \end{array}
    \end{array}
    
    Derivation
    1. Split input into 2 regimes
    2. if (-.f64 (*.f64 (PI.f64) l) (*.f64 (/.f64 #s(literal 1 binary64) (*.f64 F F)) (tan.f64 (*.f64 (PI.f64) l)))) < -5.0000000000000004e189 or -1.99999999999999989e-283 < (-.f64 (*.f64 (PI.f64) l) (*.f64 (/.f64 #s(literal 1 binary64) (*.f64 F F)) (tan.f64 (*.f64 (PI.f64) l))))

      1. Initial program 74.2%

        \[\pi \cdot \ell - \frac{1}{F \cdot F} \cdot \tan \left(\pi \cdot \ell\right) \]
      2. Add Preprocessing
      3. Taylor expanded in l around inf

        \[\leadsto \color{blue}{\ell \cdot \mathsf{PI}\left(\right)} \]
      4. Step-by-step derivation
        1. lower-*.f64N/A

          \[\leadsto \color{blue}{\ell \cdot \mathsf{PI}\left(\right)} \]
        2. lower-PI.f6483.3

          \[\leadsto \ell \cdot \color{blue}{\pi} \]
      5. Applied rewrites83.3%

        \[\leadsto \color{blue}{\ell \cdot \pi} \]

      if -5.0000000000000004e189 < (-.f64 (*.f64 (PI.f64) l) (*.f64 (/.f64 #s(literal 1 binary64) (*.f64 F F)) (tan.f64 (*.f64 (PI.f64) l)))) < -1.99999999999999989e-283

      1. Initial program 89.7%

        \[\pi \cdot \ell - \frac{1}{F \cdot F} \cdot \tan \left(\pi \cdot \ell\right) \]
      2. Add Preprocessing
      3. Step-by-step derivation
        1. lift-*.f64N/A

          \[\leadsto \mathsf{PI}\left(\right) \cdot \ell - \color{blue}{\frac{1}{F \cdot F} \cdot \tan \left(\mathsf{PI}\left(\right) \cdot \ell\right)} \]
        2. *-commutativeN/A

          \[\leadsto \mathsf{PI}\left(\right) \cdot \ell - \color{blue}{\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right) \cdot \frac{1}{F \cdot F}} \]
        3. lift-/.f64N/A

          \[\leadsto \mathsf{PI}\left(\right) \cdot \ell - \tan \left(\mathsf{PI}\left(\right) \cdot \ell\right) \cdot \color{blue}{\frac{1}{F \cdot F}} \]
        4. un-div-invN/A

          \[\leadsto \mathsf{PI}\left(\right) \cdot \ell - \color{blue}{\frac{\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right)}{F \cdot F}} \]
        5. lift-*.f64N/A

          \[\leadsto \mathsf{PI}\left(\right) \cdot \ell - \frac{\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right)}{\color{blue}{F \cdot F}} \]
        6. associate-/r*N/A

          \[\leadsto \mathsf{PI}\left(\right) \cdot \ell - \color{blue}{\frac{\frac{\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right)}{F}}{F}} \]
        7. lower-/.f64N/A

          \[\leadsto \mathsf{PI}\left(\right) \cdot \ell - \color{blue}{\frac{\frac{\tan \left(\mathsf{PI}\left(\right) \cdot \ell\right)}{F}}{F}} \]
        8. lower-/.f6489.7

          \[\leadsto \pi \cdot \ell - \frac{\color{blue}{\frac{\tan \left(\pi \cdot \ell\right)}{F}}}{F} \]
      4. Applied rewrites89.7%

        \[\leadsto \pi \cdot \ell - \color{blue}{\frac{\frac{\tan \left(\pi \cdot \ell\right)}{F}}{F}} \]
      5. Taylor expanded in l around 0

        \[\leadsto \color{blue}{\ell \cdot \left(\mathsf{PI}\left(\right) - \frac{\mathsf{PI}\left(\right)}{{F}^{2}}\right)} \]
      6. Step-by-step derivation
        1. sub-negN/A

          \[\leadsto \ell \cdot \color{blue}{\left(\mathsf{PI}\left(\right) + \left(\mathsf{neg}\left(\frac{\mathsf{PI}\left(\right)}{{F}^{2}}\right)\right)\right)} \]
        2. mul-1-negN/A

          \[\leadsto \ell \cdot \left(\mathsf{PI}\left(\right) + \color{blue}{-1 \cdot \frac{\mathsf{PI}\left(\right)}{{F}^{2}}}\right) \]
        3. lower-*.f64N/A

          \[\leadsto \color{blue}{\ell \cdot \left(\mathsf{PI}\left(\right) + -1 \cdot \frac{\mathsf{PI}\left(\right)}{{F}^{2}}\right)} \]
        4. mul-1-negN/A

          \[\leadsto \ell \cdot \left(\mathsf{PI}\left(\right) + \color{blue}{\left(\mathsf{neg}\left(\frac{\mathsf{PI}\left(\right)}{{F}^{2}}\right)\right)}\right) \]
        5. sub-negN/A

          \[\leadsto \ell \cdot \color{blue}{\left(\mathsf{PI}\left(\right) - \frac{\mathsf{PI}\left(\right)}{{F}^{2}}\right)} \]
        6. lower--.f64N/A

          \[\leadsto \ell \cdot \color{blue}{\left(\mathsf{PI}\left(\right) - \frac{\mathsf{PI}\left(\right)}{{F}^{2}}\right)} \]
        7. lower-PI.f64N/A

          \[\leadsto \ell \cdot \left(\color{blue}{\mathsf{PI}\left(\right)} - \frac{\mathsf{PI}\left(\right)}{{F}^{2}}\right) \]
        8. lower-/.f64N/A

          \[\leadsto \ell \cdot \left(\mathsf{PI}\left(\right) - \color{blue}{\frac{\mathsf{PI}\left(\right)}{{F}^{2}}}\right) \]
        9. lower-PI.f64N/A

          \[\leadsto \ell \cdot \left(\mathsf{PI}\left(\right) - \frac{\color{blue}{\mathsf{PI}\left(\right)}}{{F}^{2}}\right) \]
        10. unpow2N/A

          \[\leadsto \ell \cdot \left(\mathsf{PI}\left(\right) - \frac{\mathsf{PI}\left(\right)}{\color{blue}{F \cdot F}}\right) \]
        11. lower-*.f6488.2

          \[\leadsto \ell \cdot \left(\pi - \frac{\pi}{\color{blue}{F \cdot F}}\right) \]
      7. Applied rewrites88.2%

        \[\leadsto \color{blue}{\ell \cdot \left(\pi - \frac{\pi}{F \cdot F}\right)} \]
      8. Taylor expanded in F around 0

        \[\leadsto \ell \cdot \left(-1 \cdot \color{blue}{\frac{\mathsf{PI}\left(\right)}{{F}^{2}}}\right) \]
      9. Step-by-step derivation
        1. Applied rewrites86.4%

          \[\leadsto \ell \cdot \frac{\pi}{\color{blue}{F \cdot \left(-F\right)}} \]
        2. Taylor expanded in F around 0

          \[\leadsto -1 \cdot \color{blue}{\frac{\ell \cdot \mathsf{PI}\left(\right)}{{F}^{2}}} \]
        3. Step-by-step derivation
          1. Applied rewrites86.4%

            \[\leadsto \frac{\ell \cdot \pi}{\color{blue}{F \cdot \left(-F\right)}} \]
        4. Recombined 2 regimes into one program.
        5. Final simplification83.7%

          \[\leadsto \begin{array}{l} \mathbf{if}\;\pi \cdot \ell + \tan \left(\pi \cdot \ell\right) \cdot \frac{-1}{F \cdot F} \leq -5 \cdot 10^{+189}:\\ \;\;\;\;\pi \cdot \ell\\ \mathbf{elif}\;\pi \cdot \ell + \tan \left(\pi \cdot \ell\right) \cdot \frac{-1}{F \cdot F} \leq -2 \cdot 10^{-283}:\\ \;\;\;\;\frac{\pi \cdot \ell}{F \cdot \left(-F\right)}\\ \mathbf{else}:\\ \;\;\;\;\pi \cdot \ell\\ \end{array} \]
        6. Add Preprocessing

        Reproduce

        ?
        herbie shell --seed 2024228 
        (FPCore (F l)
          :name "VandenBroeck and Keller, Equation (6)"
          :precision binary64
          (- (* PI l) (* (/ 1.0 (* F F)) (tan (* PI l)))))