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 r21622595 = x;
        double r21622596 = 1.0;
        double r21622597 = r21622595 + r21622596;
        double r21622598 = sqrt(r21622597);
        double r21622599 = sqrt(r21622595);
        double r21622600 = r21622598 - r21622599;
        double r21622601 = y;
        double r21622602 = r21622601 + r21622596;
        double r21622603 = sqrt(r21622602);
        double r21622604 = sqrt(r21622601);
        double r21622605 = r21622603 - r21622604;
        double r21622606 = r21622600 + r21622605;
        double r21622607 = z;
        double r21622608 = r21622607 + r21622596;
        double r21622609 = sqrt(r21622608);
        double r21622610 = sqrt(r21622607);
        double r21622611 = r21622609 - r21622610;
        double r21622612 = r21622606 + r21622611;
        double r21622613 = t;
        double r21622614 = r21622613 + r21622596;
        double r21622615 = sqrt(r21622614);
        double r21622616 = sqrt(r21622613);
        double r21622617 = r21622615 - r21622616;
        double r21622618 = r21622612 + r21622617;
        return r21622618;
}