[pygame] exact algebraic numbers?

[Michael George <mdgeorge@xxxxxxxxxxxxxx>]

Hello,

For my game I need to represent right isosceles triangles, and do 
operations including translation and rotation in 15 degree increments.  
Unfortunately, I cannot tolerate rounding error, because it will cause 
bad visual and gameplay artifacts.  I'm thinking of representing points 
as vectors where the components are of the form

a + b * sqrt(2) + c * sqrt(3) + d * sqrt(6)

where a, b, c, and d are rationals.  I believe numbers of this form are 
sufficient for my purposes, although I haven't worked out all the proofs 
yet.  Anyway, I was wondering if anyone has done anything similar and 
can suggest a library I can use for manipulating such vectors before I 
go off and implement it myself.

Thanks!

--Mike