How To Compute Average Directional Index (ADX) using Lua?

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function calculate_ADX(high, low, close, period)
    local sum_TR = 0
    local sum_DMplus = 0
    local sum_DMminus = 0

    local TR_list = {}
    local DMplus_list = {}
    local DMminus_list = {}

    for i=2, #close do
        local TR = math.max(high[i] - low[i], math.abs(high[i] - close[i-1]), math.abs(low[i] - close[i-1]))
        TR_list[i] = TR

        local DMplus = 0
        local DMminus = 0

        if high[i] - high[i-1] > low[i-1] - low[i] and high[i] - high[i-1] > 0 then
            DMplus = high[i] - high[i-1]
        end

        if low[i-1] - low[i] > high[i] - high[i-1] and low[i-1] - low[i] > 0 then
            DMminus = low[i-1] - low[i]
        end

        DMplus_list[i] = DMplus
        DMminus_list[i] = DMminus

        if i > period then
            sum_TR = sum_TR + TR_list[i]
            sum_DMplus = sum_DMplus + DMplus_list[i]
            sum_DMminus = sum_DMminus + DMminus_list[i]
        end
    end

    local DX = (math.abs(sum_DMplus - sum_DMminus) / sum_TR) * 100
    local ADX = (DX + ((period - 1) * previous_ADX)) / period

    return ADX
end