Sorted-window percentile at zero-based rank (period-1)*percentage/100,
interpolating its adjacent values. Ties retain multiplicity; endpoints are
the minimum and maximum. A full period includes the current bar; warmup is
NaN. Missing values propagate by default; skip collects finite observations
and holds across gaps. Invalid periods or percentages outside 0..100 throw
RangeError; unknown missing policies throw TypeError.
Sorted-window percentile at zero-based rank (period-1)*percentage/100, interpolating its adjacent values. Ties retain multiplicity; endpoints are the minimum and maximum. A full period includes the current bar; warmup is NaN. Missing values propagate by default;
skipcollects finite observations and holds across gaps. Invalid periods or percentages outside 0..100 throw RangeError; unknown missing policies throw TypeError.