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 r8015 = 1.0;
        double r8016 = atan2(1.0, 0.0);
        double r8017 = 4.0;
        double r8018 = r8016 / r8017;
        double r8019 = r8015 / r8018;
        double r8020 = f;
        double r8021 = r8018 * r8020;
        double r8022 = exp(r8021);
        double r8023 = -r8021;
        double r8024 = exp(r8023);
        double r8025 = r8022 + r8024;
        double r8026 = r8022 - r8024;
        double r8027 = r8025 / r8026;
        double r8028 = log(r8027);
        double r8029 = r8019 * r8028;
        double r8030 = -r8029;
        return r8030;
}