The HighPass-LowPass Roofing Filter was created by John Ehlers (Cycle Analytics For Traders pg78) and this is a variation of a roofing filter that will let you know which direction the stock is trending. If it falls below 0 then the stock is in a downtrend and if it rises above 0 then it is an uptrend. Buy when the indicator line is green and sell when it is red.
Let me know if there are other scripts you would like me to publish or if you want something custom done!