Exponetial Interpolation VBA Code

Hello folks,

does any one have a VBA Code for Exponential Interpolation in Excel? I
have the formula but since I am a "new guy" at VBA programming I am
having a hard time trying to implement it.

Formula:

ExpInterp = { (1+Pi)^Di  * [(1+ Pi+1)^(Di+1)/(1+Pi)^Di]^((Dint-Di)/(Di
+1-Di)) }^(1/Dint)-1

Where: Pi and Pi+1 are points in the Y vector (e.g. points in a term
structure)
           Di and Di+1 are points in the X vector (e.g. business days
--numbers or dates)
           Dint the date of which you want the interpolation (it has
to be a number between Di and Di+1


Thanks in advance.