 Median-of-three pivot selection

Choose the median value among the first, middle and last entries of an active array segment. For at least three distinct sampled values, the selected value cannot be the whole segment's minimum or maximum. It can still be the second-smallest or second-largest value, so a balanced split does not follow. Coincident sample indices in segments of length one or two can be handled by the same comparison code. Ties must also have a defined branch policy.