// Licensed under the Apache License, Version 2.0
// © mihakralj
//@version=6
indicator("Rate of Change Percentage (ROCP)", "ROCP", overlay=false)

//@function Calculates percentage Rate of Change between current price and N periods ago
//@param source Source price series
//@param length Lookback period
//@returns Percentage price change value
rocp(series float source, simple int length)=>
    if length<=0
        runtime.error("Length must be greater than 0")
    var int count = 0
    float change = na
    if not na(source[count]) and source[count] != 0
        change := 100 * (source - source[count]) / source[count]
        count := math.min(count + 1, length)
    change

// ---------- Main loop ----------

// Inputs
i_source = input.source(close, "Source")
i_length = input.int(9, "Length", minval=1)

// Calculate ROCP
float rocp_val = rocp(i_source, i_length)

// Plot
plot(rocp_val, "ROCP", color=color.yellow, linewidth=2)