Changes in Round4

[Xavier-Francois Roblot <roblot@math.univ-lyon1.fr>]

Dear all,

I have committed a number of changes to the CVS version of PARI/GP
Round4 algorithm (essentially to fix some precision issues). This is the
algorithm used to compute maximal orders of number fields (functions:
nfbasis, nfdisc, nfinit...) and factorize polynomials over the p-adic
numbers (function: factorpadic). I'll be glad to hear about any
bugs/regressions resulting from these changes. Note that since I fixed
parts of the old version where it was cutting corners, the new version
could show a small performance loss in some examples. Significant
improvements are not impossible (though not very likely) as I also fixed
some slight inefficiencies. I'll be happy to hear about those too. In
general, I'm very much interested in examples of polynomials for which
the algorithm performs poorly (compared to the degree and the size of
the discriminant). 

Have fun,

Xavier