On Wed, 11 Nov 2009 19:28:19 -0800, Luna Moon wrote:

> x^6- p1*x^5-p2*x^4-p3*x^3-p4*x^2-p5*x - p6 = 0,
>
> where p1+...+p6=1，
>
> we know one root must be 1; other than that, under what conditions will
> we be able to have the remain roots to be inside the unit circle?

Search for "Schur stability test" -- perhaps that'll help.

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