We analyze different measures for the backward error of a set of numerical approximations for the roots of a polynomial. We focus mainly on the element-wise mixed backward error introduced by Mastronardi and Van Dooren, and the tropical backward error introduced by Tisseur and Van Barel. We show that these measures are equivalent under suitable assumptions. We also show relations between these measures and the classical element-wise and norm-wise backward error measures.
Fast and backward stable computation of roots of polynomials, Part II: backward error analysis; companion matrix and companion pencil
Universidad Autónoma de Madrid(马德里自治大学);Nazarbayev University(纳扎尔巴耶夫大学);Istituto di Scienza e Tecnologie dell Informazione ‘A. Faedo’ (ISTI), CNR(意大利国家研究委员会信息科学与技术研究所(ISTi));University of Leuven, KU Leuven(鲁汶大学);Washington State University(华盛顿州立大学)
Polynomial Root Isolation by Means of Root Radii Approximation
Lehman College and the Graduate Center of the City University of New York(纽约市立大学莱曼学院和研究生院);The Graduate Center of the City University of New York(纽约市立大学研究生院)
On computing root polynomials and minimal bases of matrix pencils
我们重温根多项式的概念,在[F。Dopico和V. Noferini,Root polynomials and their role in the矩阵论polynomials,线性代数Appl.584:37- 78,2020],并示出了在矩阵束的情况下如何有效地计算它们。阶梯算法隐式地计算所谓的零方向,如在[P. Van Dooren,传递函数的零方向的计算,IEEE第32届CDC会议录,3132- 3137,1993]中所定义的。然而,零方向通常不提供关于部分多重性和最小索引的正确信息。这些指标,而不是提供了两个特殊情况下的零方向,即根多项式和向量的最小基础的铅笔。我们展示了如何提取,从块三角铅笔的阶梯算法计算,一个最小的基础和一个最大的一组根多项式在一个有效的方式。此外,我们认为,根多项式的计算精度可以提高利用迭代加细。