It works by checking if the price is currently in an uptrend and if it crosses the 20 .
If it crosses the 20 and its in and uptrend it will post a BUY SIGNAL.
If it crosses the 20 and its in and down it will post a SELL SIGNAL.
The red line is the highest close of the previous 8 bars --- This is resistance
The green line is the lowest close of the previous 8 bars -- This is support
study(title="Tony's EMA Scalper - Buy / Sell", shorttitle="TUX EMA Scalper", overlay=true) len = input(20, minval=1, title="Length") src = input(close, title="Source") out = ema(src, len) plot(out, title="EMA", color=blue) last8h = highest(close, 8) lastl8 = lowest(close, 8) plot(last8h, color=red, linewidth=2) plot(lastl8, color=green, linewidth=2) bearish = cross(close,out) == 1 and close > close bullish = cross(close,out) == 1 and close < close plotshape(bearish, color=red, style=shape.arrowdown, text="Sell", location=location.abovebar) plotshape(bullish, color=green, style=shape.arrowup, text="Buy", location=location.belowbar)
For this it would look like this:
alertcondition(bearish == true, title="Buy Alert", message="Something to tell you to buy")
alertcondition(bullish == true, title="Sell Alert", message="Something to tell you to sell")
I haven't tried running that but to give you an idea on how to do it.