It looks like we will be upgrading to the newest version of XPP. Does the newest version of XPP support floating point math yet?
Nothing has been done in the XPP "macro language" to support floating point math, and as far as I know there are no future plans at this time to do so.
The suggestions already given to use XyPerl are good ones.
However, perhaps you might want to enter something for this on the SDL XPP Ideas page.
If you do so (and this applies to any Ideas that get entered there), please be as detailed as possible.