bb_lower

Parameters

Bollinger Bands Lower - bb_lower(source, period, num_stdev, matype="sma")

Calculates the lower Bollinger Band, which represents the lower volatility boundary

based on standard deviations below a moving average.

• source (field): Data series
• period (int): MA and stdev period (commonly 20)
• num_stdev (float): Standard deviations (commonly 2.0)
• matype (str, optional): MA type ["sma", "ema", "wma", "wilder"], default "sma"

Formula

Lower = MA - (num_stdev * STDEV)

Examples

close < bb_lower(close, 20, 2);  // Price breakdown below upper band

/* price pierced below lower band (2.5 deviations), but closed above */
low < bb_lower(close, 20, 2.5) and close > bb_lower(close, 20, 2.5);

/* lower bollinger band falling (expanding volatility) for 3 consecutive bars */
falling(bb_lower(close, 20, 2.0), 3) == true;

/* lower bollinger band rising (contracting volatility) for 3 consecutive bars */
rising(bb_upper(close, 20, 2.0), 3) == true;

Returns

Float (lower band value)

See Also