The indicator plots a price channel using the Hodrick-Prescott Filter.

The first step is to calculate the smoothed values of Close prices. After that it smoothed again with higher smoothing period. As a result we will have HP and HPSlow. On the next step we calculate the standard deviation HP relative to HPSlow and construct the channel.

The indicator prints the ratio of a full channel width to HPSlow[0], presented in percents. This text can be easily moved at any place on the chart - just drag it with double mouse click and move.

We have used the HPF (Hodrick-Prescott Filter) function from https://www.mql4.com/ for smoothing.

Indicator input parameters:

• HP Fast Period – smoothing period of the HP;
• HP Slow Period - smoothing period of the HPSlow.