Tom Utley version of Augen Price Spike Indicator

[Gatekeeper]

# Tom Utley 3-17-2009
# Thanks to Jeff Augen
# Price Spikes in Standard Deviations
declare lower;
input length = 20;
def closeLog = Log(close[1] / close[2]);
def SDev = stdev(closeLog,length) * Sqrt(length / (length-1));
def m= SDev * close[1];
plot spike = (close[0] - close[1]) / m;
spike.setPaintingStrategy(PaintingStrategy.HISTOGRAM);
spike.AssignValueColor(if close > close[3] then Color.UPTICK else if close < close[1] then Color.DOWNTICK else GetColor(1));