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Fix moved median-of-medians sample bounds for RNG 1.7 #218

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Fix moved median-of-medians sample bounds for RNG 1.7 #218

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18 changes: 14 additions & 4 deletions .../examples-jmh/src/main/java/org/apache/commons/numbers/examples/jmh/arrays/Partition.java
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Original file line number Diff line number Diff line change
Expand Up @@ -6669,11 +6669,21 @@ private int pivotMedianOfMedians(SPEPartition part, double[] a, int l, int r, in
int m = (l + rr + 1) >>> 1;
// mutual recursion
linearSelect(part, a, l, rr, m, m, bounds);
// bounds contains the range of the pivot.
// return the upper pivot and record the end of the range.
m = bounds[1];
// The selected index is a valid pivot. Do not reuse the returned bounds as
// an equal-value range: recursive sample movement can widen them. Instead,
// identify the contiguous equal range around the selected index.
final double v = a[m];
int lp = m;
while (lp > l && a[lp - 1] == v) {
--lp;
}
int p = m;
while (p < rr && a[p + 1] == v) {
++p;
}
bounds[0] = lp;
bounds[1] = rr;
return m;
return p;
}

/**
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