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 r8148 = 1.0;
        double r8149 = atan2(1.0, 0.0);
        double r8150 = 4.0;
        double r8151 = r8149 / r8150;
        double r8152 = r8148 / r8151;
        double r8153 = f;
        double r8154 = r8151 * r8153;
        double r8155 = exp(r8154);
        double r8156 = -r8154;
        double r8157 = exp(r8156);
        double r8158 = r8155 + r8157;
        double r8159 = r8155 - r8157;
        double r8160 = r8158 / r8159;
        double r8161 = log(r8160);
        double r8162 = r8152 * r8161;
        double r8163 = -r8162;
        return r8163;
}