Re: [Bug-gsl] Bug in polynomial root finder

[Munagala Ramanath]

Thanks for the response.

I have run it on more than 1.6 million polynomials of order 15 and this is
the only one on which it has problems.

I've also run it on some polynomials of order 18 and again it had no problems.

So it seems the order is not the problem, just some corner case with this
particular polynomial.

Ram


________________________________
From: Brian Gough <address@hidden>
To: Munagala Ramanath <address@hidden>
Cc: "address@hidden" <address@hidden>
Sent: Friday, November 4, 2011 3:37 AM
Subject: Re: [Bug-gsl] Bug in polynomial root finder

At Sat, 29 Oct 2011 08:22:53 -0700 (PDT),
Munagala Ramanath wrote:
> # shows bug in GSL polynomial root finder
> p = [1, -4, 2, 10, -17, 10, 6, -16, 12, -16, 16, -8, 28, -8, -48, 32]
> roots = GSL::Poly[ p.reverse ].solve

Thanks for the email.  I think that is just a limitation of the solver
algorithm rather than a bug. The algorithm does not work for
arbitrarily high orders and 15th order is probably too high.

-- 
Brian Gough