The 3 Pole Butterworth Filter was created by John Ehlers (Cycle Analytics For Traders pg 32) and this is a nice filter that follows the price very closely. Buy when the indicator is green and sell when it turns red.
This was a custom request so let me know if you would like me to publish any other scripts or if you want something custom done!
Based on the exponential averaging method with lag reduction, this filter allow for smoother results thanks to a multi-poles approach. Translated and modified from the Non-Linear Kalman Filter from Mladen Rakic 01/07/19 www.mql5.com
length control the amount of smoothing, the poles can be from 1 to 3, higher...