// The MIT License (MIT)
// © mihakralj
//@version=6
indicator("Rate of Change (ROC)", "ROC", overlay=false)

//@function Calculates absolute Rate of Change between current price and N periods ago
//@doc https://github.com/mihakralj/pinescript/blob/main/indicators/momentum/roc.md
//@param source Source price series
//@param length Lookback period
//@returns Absolute price change value
roc(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])
        change := source - 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 ROC
float roc_val = roc(i_source, i_length)

// Plot
plot(roc_val, "ROC", color=color.yellow, linewidth=2)