commons-numbers-arrays/src/main/java/org/apache/commons/numbers/arrays/QuickSelect.java [694:704]:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
        final int n = r - l + 1;
        final int ith = k - l + 1;
        final double z = Math.log(n);
        // sample size = 0.5 * n^(2/3)
        final double s = 0.5 * Math.exp(0.6666666666666666 * z);
        final double sd = 0.5 * Math.sqrt(z * s * (n - s) / n) * Integer.signum(ith - (n >> 1));
        final int ll = Math.max(l, (int) (k - ith * s / n + sd));
        final int rr = Math.min(r, (int) (k + (n - ith) * s / n + sd));
        // Sample recursion restarts from [ll, rr]
        final int p = quickSelectAdaptive(a, ll, rr, k, k, upper, MODE_FR_SAMPLING);
        return expandPartition(a, l, r, ll, rr, p, upper[0], upper);
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -



commons-numbers-arrays/src/main/java/org/apache/commons/numbers/arrays/QuickSelect.java [1953:1963]:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
        final int n = r - l + 1;
        final int ith = k - l + 1;
        final double z = Math.log(n);
        // sample size = 0.5 * n^(2/3)
        final double s = 0.5 * Math.exp(0.6666666666666666 * z);
        final double sd = 0.5 * Math.sqrt(z * s * (n - s) / n) * Integer.signum(ith - (n >> 1));
        final int ll = Math.max(l, (int) (k - ith * s / n + sd));
        final int rr = Math.min(r, (int) (k + (n - ith) * s / n + sd));
        // Sample recursion restarts from [ll, rr]
        final int p = quickSelectAdaptive(a, ll, rr, k, k, upper, MODE_FR_SAMPLING);
        return expandPartition(a, l, r, ll, rr, p, upper[0], upper);
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -