This file offers two functions:
f be a
RingElem whose value is a univariate polynomial
with rational coefficients.
SturmSeq(f)-- returns a
vector<RingElem>being the Sturm sequence of the polynomial
f(in order of decreasing degree)
NumRealRoots(f)-- returns a
long` being the number of real roots ``fhas.
The implementation is naive and simple; this is OK for small examples. Currently it computes a primitive PRS; seems adequate for smallish tests.
Clears denominators, but I'm not sure why