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

\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 r66426692 = 2.0;
        double r66426693 = t;
        double r66426694 = 3.0;
        double r66426695 = pow(r66426693, r66426694);
        double r66426696 = l;
        double r66426697 = r66426696 * r66426696;
        double r66426698 = r66426695 / r66426697;
        double r66426699 = k;
        double r66426700 = sin(r66426699);
        double r66426701 = r66426698 * r66426700;
        double r66426702 = tan(r66426699);
        double r66426703 = r66426701 * r66426702;
        double r66426704 = 1.0;
        double r66426705 = r66426699 / r66426693;
        double r66426706 = pow(r66426705, r66426692);
        double r66426707 = r66426704 + r66426706;
        double r66426708 = r66426707 - r66426704;
        double r66426709 = r66426703 * r66426708;
        double r66426710 = r66426692 / r66426709;
        return r66426710;
}

Reproduce

herbie shell --seed 2019121 
(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