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 r640320 = x;
        double r640321 = 1.0;
        double r640322 = r640320 + r640321;
        double r640323 = sqrt(r640322);
        double r640324 = sqrt(r640320);
        double r640325 = r640323 - r640324;
        double r640326 = y;
        double r640327 = r640326 + r640321;
        double r640328 = sqrt(r640327);
        double r640329 = sqrt(r640326);
        double r640330 = r640328 - r640329;
        double r640331 = r640325 + r640330;
        double r640332 = z;
        double r640333 = r640332 + r640321;
        double r640334 = sqrt(r640333);
        double r640335 = sqrt(r640332);
        double r640336 = r640334 - r640335;
        double r640337 = r640331 + r640336;
        double r640338 = t;
        double r640339 = r640338 + r640321;
        double r640340 = sqrt(r640339);
        double r640341 = sqrt(r640338);
        double r640342 = r640340 - r640341;
        double r640343 = r640337 + r640342;
        return r640343;
}