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 r18705596 = x;
        double r18705597 = 1.0;
        double r18705598 = r18705596 + r18705597;
        double r18705599 = sqrt(r18705598);
        double r18705600 = sqrt(r18705596);
        double r18705601 = r18705599 - r18705600;
        double r18705602 = y;
        double r18705603 = r18705602 + r18705597;
        double r18705604 = sqrt(r18705603);
        double r18705605 = sqrt(r18705602);
        double r18705606 = r18705604 - r18705605;
        double r18705607 = r18705601 + r18705606;
        double r18705608 = z;
        double r18705609 = r18705608 + r18705597;
        double r18705610 = sqrt(r18705609);
        double r18705611 = sqrt(r18705608);
        double r18705612 = r18705610 - r18705611;
        double r18705613 = r18705607 + r18705612;
        double r18705614 = t;
        double r18705615 = r18705614 + r18705597;
        double r18705616 = sqrt(r18705615);
        double r18705617 = sqrt(r18705614);
        double r18705618 = r18705616 - r18705617;
        double r18705619 = r18705613 + r18705618;
        return r18705619;
}