I use the following PCF for finding the price change over the last 5 days ending today

(C - C5) / C5 * 100

I am trying to write a PCF fo finding the price change over the last 5 days at yesterdays close, two days ago close, three days etc for backtesting

I wondered if this is the correct PCF for 5 day price change at yesterdays close.

(C1 - C5.1) / C5.1 * 100

Is this the correct PCF for 5 day price change at close 2 days ago

 (C2- C5.2) / C5.2 * 100

Thanks very much

You can't add a second bars ago parameter. You need to increment the existing bars ago parameters.

So a 1-bar ago version of:

(C - C5) / C5 * 100

Would be:

(C1 - C6) / C6 * 100

And a 2-bars ago version would be:

(C2 - C7) / C7 * 100

PCF Formula Descriptions
Handy PCF example formulas to help you learn the syntax of PCFs!