A Simple Function for a simple mind?

Hey Folks,

My brain does not seem to be working, and my reference materials are not where I am....I need to know if VB has a function that will return the amount of interest for a given period ie: InterestAmount = FunctionName(DueDate, Now, InterestPercentage, PrincipalAmount). If not, can someone help me remember the expodential function IntrestAmount = p*e^(i*dt). I am having difficulty remembering it exactly.

Thanks in advance,

Hunter