Cannot sample enough valid points. (more)

\[\left(\left(\left(\sqrt{x + 1} - \sqrt{x}\right) + \left(\sqrt{y + 1} - \sqrt{y}\right)\right) + \left(\sqrt{z + 1} - \sqrt{z}\right)\right) + \left(\sqrt{t + 1} - \sqrt{t}\right)\]
\left(\left(\left(\sqrt{x + 1} - \sqrt{x}\right) + \left(\sqrt{y + 1} - \sqrt{y}\right)\right) + \left(\sqrt{z + 1} - \sqrt{z}\right)\right) + \left(\sqrt{t + 1} - \sqrt{t}\right)
double f(double x, double y, double z, double t) {
        double r8788 = x;
        double r8789 = 1.0;
        double r8790 = r8788 + r8789;
        double r8791 = sqrt(r8790);
        double r8792 = sqrt(r8788);
        double r8793 = r8791 - r8792;
        double r8794 = y;
        double r8795 = r8794 + r8789;
        double r8796 = sqrt(r8795);
        double r8797 = sqrt(r8794);
        double r8798 = r8796 - r8797;
        double r8799 = r8793 + r8798;
        double r8800 = z;
        double r8801 = r8800 + r8789;
        double r8802 = sqrt(r8801);
        double r8803 = sqrt(r8800);
        double r8804 = r8802 - r8803;
        double r8805 = r8799 + r8804;
        double r8806 = t;
        double r8807 = r8806 + r8789;
        double r8808 = sqrt(r8807);
        double r8809 = sqrt(r8806);
        double r8810 = r8808 - r8809;
        double r8811 = r8805 + r8810;
        return r8811;
}