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 r8154 = 1.0;
        double r8155 = atan2(1.0, 0.0);
        double r8156 = 4.0;
        double r8157 = r8155 / r8156;
        double r8158 = r8154 / r8157;
        double r8159 = f;
        double r8160 = r8157 * r8159;
        double r8161 = exp(r8160);
        double r8162 = -r8160;
        double r8163 = exp(r8162);
        double r8164 = r8161 + r8163;
        double r8165 = r8161 - r8163;
        double r8166 = r8164 / r8165;
        double r8167 = log(r8166);
        double r8168 = r8158 * r8167;
        double r8169 = -r8168;
        return r8169;
}