Ralf, On Sun, 20 Jun 2004, Ralf Stephan wrote:
Please include. This works with any polynomial.
Hmm, this ties in with the discussion we had with Chris about expand() inside series expansion and certain cancellations. In your code below, I think an unexpanded polynomial a or b would lead to some bloat because of the problems with degree/ldegree discussed so far. In Ginsh:
ldegree((x+2)*(x+2)*(x+2) - (2+x)*(4+x),x); 0 ldegree(expand((x+2)*(x+2)*(x+2) - (2+x)*(4+x)),x); 1
Methinks you should just call expand inside resultant(). Note that on large expanded polynomials, expand is an O(1) operation due to the expanded flag. Also, I think the statement "Resultants are commutative" ought to be clarified just a little bit. Regards -richy. -- Richard B. Kreckel <http://www.ginac.de/~kreckel/>