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 r22663879 = x;
        double r22663880 = 1.0;
        double r22663881 = r22663879 + r22663880;
        double r22663882 = sqrt(r22663881);
        double r22663883 = sqrt(r22663879);
        double r22663884 = r22663882 - r22663883;
        double r22663885 = y;
        double r22663886 = r22663885 + r22663880;
        double r22663887 = sqrt(r22663886);
        double r22663888 = sqrt(r22663885);
        double r22663889 = r22663887 - r22663888;
        double r22663890 = r22663884 + r22663889;
        double r22663891 = z;
        double r22663892 = r22663891 + r22663880;
        double r22663893 = sqrt(r22663892);
        double r22663894 = sqrt(r22663891);
        double r22663895 = r22663893 - r22663894;
        double r22663896 = r22663890 + r22663895;
        double r22663897 = t;
        double r22663898 = r22663897 + r22663880;
        double r22663899 = sqrt(r22663898);
        double r22663900 = sqrt(r22663897);
        double r22663901 = r22663899 - r22663900;
        double r22663902 = r22663896 + r22663901;
        return r22663902;
}