![](https://secure.gravatar.com/avatar/802b07155a8ab3996b825eca778f770e.jpg?s=120&d=mm&r=g)
Nadav Horesh wrote:
I tested the problem with: 1. Numeric 23.1 under python 2.3.2 2. numarray 0.8 (I made a copy of the Scientific package where all calls to Numeric were replaced to numarray), under python 2.3.2 There results where about the same -- high coefficients for the 5th order polynomials. I would expect reliable fit for a high order polynomials only under very special circumstances, so this is not a big surprise.
Thanks for your efforts. The polynomial we're trying to fit here is not extremely unstable. As I said, with Numeric 17.1.2 my class of problems used to be stable up to at least 9th order. I really suspect a bug was introduced here which is difficult to pinpoint because everybody reacts the natural way: this is an intrinsicly unstable problem, so it is not unexpected. Somehow it could have been better, though! I managed to work around the problem so far by using a different solver also built in to Scientific Python, so I am saved so far. Regards, Rob -- Rob W.W. Hooft || rob@hooft.net || http://www.hooft.net/people/rob/