There is the indicator BollingerBand and I can change the parameter of standard deviation. But as I want to use it in my screener I can get BollingDown(20) and BollingerUp(20). How can I change the stabdard deviation?
This instruction use the default parameter of a Bollinger band = 2 deviations from the mean. If you want to find the bollinger up band with only 1 deviation, you have to re-code it yourself:
dev = 1 //quantity of deviation
avg = average[20](close) //mean
BollUp = avg+std[20](close)*dev //Bollinger Up value