Fast Computation of the Zeros of a Polynomial via Factorization of the Companion Matrix
Author(s) -
Jared L. Aurentz,
Raf Vandebril,
David S. Watkins
Publication year - 2013
Publication title -
siam journal on scientific computing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.674
H-Index - 147
eISSN - 1095-7197
pISSN - 1064-8275
DOI - 10.1137/120865392
Subject(s) - companion matrix , mathematics , eigenvalues and eigenvectors , matrix polynomial , polynomial , residual , computation , matrix (chemical analysis) , factorization , qr decomposition , algorithm , polynomial matrix , matrix decomposition , characteristic polynomial , incomplete lu factorization , condition number , algebra over a field , pure mathematics , mathematical analysis , physics , materials science , quantum mechanics , composite material
A new fast algorithm for computing the zeros of a polynomial in $O(n^{2})$ time using $O(n)$ memory is developed. The eigenvalues of the Frobenius companion matrix are computed by applying a nonunitary analogue of Francis's implicitly shifted $QR$ algorithm to a factored form of the matrix. The algorithm achieves high speed and low memory use by preserving the factored form. It also provides a residual and an error estimate for each root. Numerical tests confirm the high speed of the algorithm.status: publishe
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