AngouriMath

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RootsEnclosed​(AngouriMath.​Entity,​AngouriMath.​Entity.​Variable)

 Method (no overloads)

Summary

A rectangle about each root of polynomial in w,
holding that root and no other; null where the polynomial does not have rational
coefficients, or the rectangles cannot be kept apart.

Remarks

Durand–Kerner's approximations z_k at this precision, each enclosed by its
Weierstrass correction w_k = p(z_k)/(a prod_{j != k} (z_k - z_j)), worked out in
intervals. Every root lies in a disk about some z_k - w_k of radius
(n - 1)|w_k|, and a disk apart from the others holds exactly one (Braess and
Hadeler). That disk is inside the one of radius n|w_k| about z_k, whose
square is the rectangle, so rectangles apart from each other hold one root each.

























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