Elder-ray Index

// 2020.7.26 version
// This indicator is for the second filter in Triple Screen Trading System which can show bearish power and bullish power
// indicator rule
// if showbull is true, show bullish power, if showbull is false, show bearish power
// if Trend is bull, buy when bearish power is getting back from the lowest but still under zero
// if Trend is bear, short when bullish power is going down from the highest but still up zero
// now only draw line but not histgram
// As for how to decide bullish market or bearish market, please check it according to the first filter of Triple Screen Trading System