Roger Hui wrote: > But do you really know the roots? You do know the roots > of the polynomial q=:1;(i.20),20.0001 , but the roots of > the polynomial p. q are a different matter. Is it possible > to represent p. q in IEEE 64-bit floating point to get > good answers for p. p. q ? > Point taken: I don't think you can.
> A warning about a polynomial root finder should say > something to the effect that PROOT finding (by any > root finder) is extremely sensitive to the coefficients. > Vide the Wilkinson monster. Agreed, noting that it gets worse as the degree increases. Using Lagrange interpolation on 3 points is probably OK, but on 10 points is probably not. Best wishes, John ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
