Hi Jay,
In the Computation Rules (option #5) of the Content Type.
The way do define your own computation rule is to use the Custom -> Free - then set up your own formula like: (a.pow(2) + b.pow(2))*c + d
Then in the fields that you want to add:
Field1: a
Field2: b
Field3: c
Field4: d
Hope that helps,
Randy