This list might be a good place for meeting XML experts, but I don't think you can assume that every XML expert knows how to solve linear equations. I think I once knew, but that was about 40 years ago, and it's not a skill you retain if you don't use it.
If you can tell us the rules you want your transformation to obey, then perhaps we can show you how to express these in XSLT.
It's probably worth studying Dimitre Novatchev's work on FXSL.
Author, XSLT 2.0 and XPath 2.0 Programmer's Reference