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 r8127 = 1.0;
        double r8128 = atan2(1.0, 0.0);
        double r8129 = 4.0;
        double r8130 = r8128 / r8129;
        double r8131 = r8127 / r8130;
        double r8132 = f;
        double r8133 = r8130 * r8132;
        double r8134 = exp(r8133);
        double r8135 = -r8133;
        double r8136 = exp(r8135);
        double r8137 = r8134 + r8136;
        double r8138 = r8134 - r8136;
        double r8139 = r8137 / r8138;
        double r8140 = log(r8139);
        double r8141 = r8131 * r8140;
        double r8142 = -r8141;
        return r8142;
}