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 r8125 = 1.0;
        double r8126 = atan2(1.0, 0.0);
        double r8127 = 4.0;
        double r8128 = r8126 / r8127;
        double r8129 = r8125 / r8128;
        double r8130 = f;
        double r8131 = r8128 * r8130;
        double r8132 = exp(r8131);
        double r8133 = -r8131;
        double r8134 = exp(r8133);
        double r8135 = r8132 + r8134;
        double r8136 = r8132 - r8134;
        double r8137 = r8135 / r8136;
        double r8138 = log(r8137);
        double r8139 = r8129 * r8138;
        double r8140 = -r8139;
        return r8140;
}