Cannot sample enough valid points. (more)

\[\left(\left(\left(\sqrt{x + 1.0} - \sqrt{x}\right) + \left(\sqrt{y + 1.0} - \sqrt{y}\right)\right) + \left(\sqrt{z + 1.0} - \sqrt{z}\right)\right) + \left(\sqrt{t + 1.0} - \sqrt{t}\right)\]
\left(\left(\left(\sqrt{x + 1.0} - \sqrt{x}\right) + \left(\sqrt{y + 1.0} - \sqrt{y}\right)\right) + \left(\sqrt{z + 1.0} - \sqrt{z}\right)\right) + \left(\sqrt{t + 1.0} - \sqrt{t}\right)
double f(double x, double y, double z, double t) {
        double r21770094 = x;
        double r21770095 = 1.0;
        double r21770096 = r21770094 + r21770095;
        double r21770097 = sqrt(r21770096);
        double r21770098 = sqrt(r21770094);
        double r21770099 = r21770097 - r21770098;
        double r21770100 = y;
        double r21770101 = r21770100 + r21770095;
        double r21770102 = sqrt(r21770101);
        double r21770103 = sqrt(r21770100);
        double r21770104 = r21770102 - r21770103;
        double r21770105 = r21770099 + r21770104;
        double r21770106 = z;
        double r21770107 = r21770106 + r21770095;
        double r21770108 = sqrt(r21770107);
        double r21770109 = sqrt(r21770106);
        double r21770110 = r21770108 - r21770109;
        double r21770111 = r21770105 + r21770110;
        double r21770112 = t;
        double r21770113 = r21770112 + r21770095;
        double r21770114 = sqrt(r21770113);
        double r21770115 = sqrt(r21770112);
        double r21770116 = r21770114 - r21770115;
        double r21770117 = r21770111 + r21770116;
        return r21770117;
}