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 r8121 = 1.0;
        double r8122 = atan2(1.0, 0.0);
        double r8123 = 4.0;
        double r8124 = r8122 / r8123;
        double r8125 = r8121 / r8124;
        double r8126 = f;
        double r8127 = r8124 * r8126;
        double r8128 = exp(r8127);
        double r8129 = -r8127;
        double r8130 = exp(r8129);
        double r8131 = r8128 + r8130;
        double r8132 = r8128 - r8130;
        double r8133 = r8131 / r8132;
        double r8134 = log(r8133);
        double r8135 = r8125 * r8134;
        double r8136 = -r8135;
        return r8136;
}