> ), written in Java for PDAs and it seems pretty fast and light :
>                 rat(3/5)+rat(1/3) gives 14/15 as answer !
>
> I wouldn't say that XPath can't perform rational arithmetic but rather that rational arithmetic is not yet implemented for XPath. Benefits > for scientists, financials,... Integrating this with XForms will permit users to set fields in web applications without a calculator always > at hand.

If you put formulas like that in the data fields of XML, then you are coming back to raw text data that you will have to parse, losing the power of XML ? Why not use MathML and tools associated ?

Regards
Nico
http://debeissat.nicolas.free.fr/