What I would like to do is to be able to sort in a column the price difference between Weekly High minus weekly low over say three weeks, to find how much difference on average for 3 weeks .

Example: 2 weeks ago  10.50H 9.45L = 1.05 / 9.45 = 11.11%.  1 weeks ago 10.95H - 10.35L = .60 / 10.35 = 5.79%. Current week  11.40 - 10.35 = 1.05 / 10.35 = 10.14%.     

11.11% + 5.79% + 10.14% = 27.04% / 3 = 9.01% .  Giving a return of 9.01% rise/ gain  for the average of 3 weeks, based on low of each week. 

I need to know how to write the PCF so I can add it as column in a watch list.

Please try the following Indicator Formula using a weekly time frame.

100 * ((H / L + H1 / L1 + H2 / L2) / 3 - 1)

Or the following Indicator Formula using a daily time frame.

100 * ((MAXH5 / MINL5 + MAXH5.5 / MINL5.5 + MAXH5.10 / MINL5.10) / 3 - 1)

Note that these are different things. The first is looking at calendar weeks running from Monday through Friday including the current week even if we haven't hit Friday yet.

The second is using 5 trading days instead of calendar weeks.

The results should match on Fridays where there have not been any Market Holidays during those three weeks.

PCF Formula Descriptions

THANK YOU SO VERY MUCH

You're welcome.