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 r8021 = 1.0;
        double r8022 = atan2(1.0, 0.0);
        double r8023 = 4.0;
        double r8024 = r8022 / r8023;
        double r8025 = r8021 / r8024;
        double r8026 = f;
        double r8027 = r8024 * r8026;
        double r8028 = exp(r8027);
        double r8029 = -r8027;
        double r8030 = exp(r8029);
        double r8031 = r8028 + r8030;
        double r8032 = r8028 - r8030;
        double r8033 = r8031 / r8032;
        double r8034 = log(r8033);
        double r8035 = r8025 * r8034;
        double r8036 = -r8035;
        return r8036;
}