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 r8018 = 1.0;
        double r8019 = atan2(1.0, 0.0);
        double r8020 = 4.0;
        double r8021 = r8019 / r8020;
        double r8022 = r8018 / r8021;
        double r8023 = f;
        double r8024 = r8021 * r8023;
        double r8025 = exp(r8024);
        double r8026 = -r8024;
        double r8027 = exp(r8026);
        double r8028 = r8025 + r8027;
        double r8029 = r8025 - r8027;
        double r8030 = r8028 / r8029;
        double r8031 = log(r8030);
        double r8032 = r8022 * r8031;
        double r8033 = -r8032;
        return r8033;
}