Module: BollingerBands

Included in:
Array
Defined in:
lib/ruby-technical-analysis/indicators/bollinger_bands.rb

Overview

Bollinger Bands indicator Returns an array containing the current upper, middle, and lower bands of the series

Instance Method Summary collapse

Instance Method Details

#bollinger_bands(period) ⇒ Object 



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# File 'lib/ruby-technical-analysis/indicators/bollinger_bands.rb', line 9

def bollinger_bands(period)
  if size < period
    raise ArgumentError,
          "Array passed to Bollinger Bands cannot be less than the period argument."
  end
  closes = last(period)
  middle = closes.sma(period)
  twice_sd = (2 * closes.standard_deviation).truncate(4)
  upper = twice_sd + middle
  lower = middle - twice_sd
  [upper, middle, lower]
end