Investment or Loan Compound Interest Rates (APY)

[Maxattax97]

I am new to TaskJuggler and I have been trying to find a way to model my "money working for me" in the form of compound interest rates. I feel as though there might be a way to do this (albeit, in a complicated fashion) with the exist tools... maybe a resource that charges to an account? But I don't know how to make it dynamic with a percentage. I'd use an arithmetic operator but I don't see a way to do that other than with e.g. days (- 1d).

This would also be useful for modeling debt, taxes, or many other percentage-based things.

[Maxattax97]

Another thing to note here... many times "annual percent yield" (APY) is used, but I have only found at most a perweek operator... so I have found myself manually dividing by 4 to generate another rate ☹️