I was wondering how built-in "roc" function in Pine is defined and calculated so I made a little research.
I examined 4 samples:
1) "roc" function itself
2) "roc" according to its description
3) price change ratio
4) price percent change ratio
The results of the first and fourth samples are identical.
So, TV built-in (source, length) = 100 * change(source, length) / source.
And it's description is incorrect.
If you didnt know it - now you know it.