Function positiveVolumeIndex

Positive Volume Index (Fosback) — negativeVolumeIndex's twin, compounding a bar's return only when that bar's volume was higher than the previous bar's:

PVI[0] = start                                   (1000 by convention)
PVI[i] = volume[i] > volume[i−1]
         ? PVI[i−1] × (1 + (close[i] − close[i−1]) / close[i−1])
         : PVI[i−1]
Copy

Every convention, edge and gap rule on negativeVolumeIndex applies unchanged — including that an unchanged volume holds, so NVI and PVI do not partition the bars between them: a flat-volume bar is compounded into neither.

Appends one column (pvi by default).