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 r8151 = 1.0;
        double r8152 = atan2(1.0, 0.0);
        double r8153 = 4.0;
        double r8154 = r8152 / r8153;
        double r8155 = r8151 / r8154;
        double r8156 = f;
        double r8157 = r8154 * r8156;
        double r8158 = exp(r8157);
        double r8159 = -r8157;
        double r8160 = exp(r8159);
        double r8161 = r8158 + r8160;
        double r8162 = r8158 - r8160;
        double r8163 = r8161 / r8162;
        double r8164 = log(r8163);
        double r8165 = r8155 * r8164;
        double r8166 = -r8165;
        return r8166;
}