Anyone know full RSI formula in metastock language???

[dburkey@xxxxxxxxxxxxxxxx]

Does anyone know the full formula for the RSI (relative strength
index)?, 

I know that metastock just uses rsi(length), but I'm trying to take the
rsi of another indicator, not the close.  

I've looked in a few books but I don't know how to translate the formula
into metastock language.

Omega Research lets you simply use RSI(x, length), where x can be
anything, even other indicators. 

Please help... I'm stuck right in the middle of a project.

Thanks, 

-dennis