Cannot sample enough valid points. (more)

\[-\frac{1}{\frac{\pi}{4}} \cdot \log \left(\frac{e^{\frac{\pi}{4} \cdot f} + e^{-\frac{\pi}{4} \cdot f}}{e^{\frac{\pi}{4} \cdot f} - e^{-\frac{\pi}{4} \cdot f}}\right)\]
-\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)
double f(double f) {
        double r8013 = 1.0;
        double r8014 = atan2(1.0, 0.0);
        double r8015 = 4.0;
        double r8016 = r8014 / r8015;
        double r8017 = r8013 / r8016;
        double r8018 = f;
        double r8019 = r8016 * r8018;
        double r8020 = exp(r8019);
        double r8021 = -r8019;
        double r8022 = exp(r8021);
        double r8023 = r8020 + r8022;
        double r8024 = r8020 - r8022;
        double r8025 = r8023 / r8024;
        double r8026 = log(r8025);
        double r8027 = r8017 * r8026;
        double r8028 = -r8027;
        return r8028;
}