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 r8014 = 1.0;
        double r8015 = atan2(1.0, 0.0);
        double r8016 = 4.0;
        double r8017 = r8015 / r8016;
        double r8018 = r8014 / r8017;
        double r8019 = f;
        double r8020 = r8017 * r8019;
        double r8021 = exp(r8020);
        double r8022 = -r8020;
        double r8023 = exp(r8022);
        double r8024 = r8021 + r8023;
        double r8025 = r8021 - r8023;
        double r8026 = r8024 / r8025;
        double r8027 = log(r8026);
        double r8028 = r8018 * r8027;
        double r8029 = -r8028;
        return r8029;
}