// Licensed under the Apache License, Version 2.0
// © mihakralj
//@version=6
indicator("Positive Volume Index (PVI)", "PVI", overlay=false)

//@function Calculates Positive Volume Index, tracks price changes on days with higher volume
//@param src Price series to use for calculation
//@param vol Volume series
//@param start_value Starting value for PVI (typically 100 or 1000)
//@returns float The PVI value
pvi(series float src, series float vol = volume, simple float start_value = 100.0) =>
    var float pvi_value = start_value
    if not (na(src) or na(vol) or na(src[1]) or na(vol[1]) or src[1] == 0.0 or vol[1] <= 0.0) and vol > vol[1]
        pvi_value := pvi_value * src / src[1]
    pvi_value

// ---------- Main Calculation ----------

// Parameters
src = input.source(close, "Price Source")

// Calculations
pvi_line = pvi(src, volume)

// Plot
plot(pvi_line, "PVI", color=color.yellow, linewidth=2)