\[\frac{2}{\left(\left(\frac{{t}^{3}}{\ell \cdot \ell} \cdot \sin k\right) \cdot \tan k\right) \cdot \left(\left(1 + {\left(\frac{k}{t}\right)}^{2}\right) + 1\right)}\]

\frac{2}{\left(\left(\frac{{t}^{3}}{\ell \cdot \ell} \cdot \sin k\right) \cdot \tan k\right) \cdot \left(\left(1 + {\left(\frac{k}{t}\right)}^{2}\right) + 1\right)}

double f(double t, double l, double k) {
        double r1799771 = 2.0;
        double r1799772 = t;
        double r1799773 = 3.0;
        double r1799774 = pow(r1799772, r1799773);
        double r1799775 = l;
        double r1799776 = r1799775 * r1799775;
        double r1799777 = r1799774 / r1799776;
        double r1799778 = k;
        double r1799779 = sin(r1799778);
        double r1799780 = r1799777 * r1799779;
        double r1799781 = tan(r1799778);
        double r1799782 = r1799780 * r1799781;
        double r1799783 = 1.0;
        double r1799784 = r1799778 / r1799772;
        double r1799785 = pow(r1799784, r1799771);
        double r1799786 = r1799783 + r1799785;
        double r1799787 = r1799786 + r1799783;
        double r1799788 = r1799782 * r1799787;
        double r1799789 = r1799771 / r1799788;
        return r1799789;
}

Reproduce

herbie shell --seed 2019132 
(FPCore (t l k)
  :name "Toniolo and Linder, Equation (10+)"
  (/ 2 (* (* (* (/ (pow t 3) (* l l)) (sin k)) (tan k)) (+ (+ 1 (pow (/ k t) 2)) 1))))

Timeout in 10.0m

Reproduce