I haven't explicitly set the ring it's working over, but all the entries of the matrix are integral.
On Monday, 20 May 2013 20:37:55 UTC-4, William wrote: > > On Mon, May 20, 2013 at 2:19 PM, Theo Belaire > <[email protected] <javascript:>> 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] <javascript:>. > > To post to this group, send email to > > [email protected]<javascript:>. > > > 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.
