\pi \cdot \ell - \frac{1}{F \cdot F} \cdot \tan \left(\pi \cdot \ell\right)\ell \cdot \pi - \left(\tan \left(\sqrt[3]{\ell} \cdot \left(\pi \cdot \left(\sqrt[3]{\ell} \cdot \sqrt[3]{\ell}\right)\right)\right) \cdot \frac{\sqrt{1}}{F}\right) \cdot \frac{\sqrt{1}}{F}double f(double F, double l) {
double r965676 = atan2(1.0, 0.0);
double r965677 = l;
double r965678 = r965676 * r965677;
double r965679 = 1.0;
double r965680 = F;
double r965681 = r965680 * r965680;
double r965682 = r965679 / r965681;
double r965683 = tan(r965678);
double r965684 = r965682 * r965683;
double r965685 = r965678 - r965684;
return r965685;
}
double f(double F, double l) {
double r965686 = l;
double r965687 = atan2(1.0, 0.0);
double r965688 = r965686 * r965687;
double r965689 = cbrt(r965686);
double r965690 = r965689 * r965689;
double r965691 = r965687 * r965690;
double r965692 = r965689 * r965691;
double r965693 = tan(r965692);
double r965694 = 1.0;
double r965695 = sqrt(r965694);
double r965696 = F;
double r965697 = r965695 / r965696;
double r965698 = r965693 * r965697;
double r965699 = r965698 * r965697;
double r965700 = r965688 - r965699;
return r965700;
}



Bits error versus F



Bits error versus l
Results
Initial program 16.5
rmApplied add-sqr-sqrt16.5
Applied times-frac16.5
Applied associate-*l*12.4
rmApplied add-cube-cbrt12.5
Applied associate-*r*12.6
Final simplification12.6
herbie shell --seed 2019200
(FPCore (F l)
:name "VandenBroeck and Keller, Equation (6)"
(- (* PI l) (* (/ 1.0 (* F F)) (tan (* PI l)))))