On Mon, May 20, 2013 at 2:19 PM, Theo Belaire <[email protected]> wrote: > I have a large computation where I need to compute the number of positive > eigenvalues of a matrix. > I am currently computing all the eigenvalues then counting how many are > positive, but I see when profiling that "{method 'roots' of > 'sage.rings.polynomial.polynomial_element.Polynomial' objects}" is taking up > most of the time. > Any way to just get sign? > Or to use estimates to speed up most of the computation, and I can recompute > any that have more than 1 positive eigenvalues exactly. I'd really like to > avoid any false negatives though. >
Can you somehow give an example of the sort of polynomials you're considering? What's the base field? RR, RealField(100), RDF, CDF, etc.? For example: R.<x> = RR['x'] f = x^50 + 7*x + 5 %timeit f.roots() 5 loops, best of 3: 97.6 ms per loop versus R.<x> = RDF['x'] f = x^50 + 7*x + 5 %timeit f.roots() 125 loops, best of 3: 5.74 ms per loop > -- > You received this message because you are subscribed to the Google Groups > "sage-support" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/sage-support?hl=en. > For more options, visit https://groups.google.com/groups/opt_out. > > -- William Stein Professor of Mathematics University of Washington http://wstein.org -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sage-support?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
