The multishift <i>QR</i> algorithm.: part II:: Aggressive early deflation

作     者：Braman, K Byers, R Mathias, R 

作者机构：Univ Kansas Dept Math Lawrence KS 66045 USA Coll William & Mary Dept Math Williamsburg VA 23187 USA 

出 版 物：《SIAM JOURNAL ON MATRIX ANALYSIS AND APPLICATIONS》 (工业与应用数学会矩阵分析和应用杂志)

年 卷 期：2002年第23卷第4期

页      面：948-973页

核心收录：

学科分类：07[理学] 070104[理学-应用数学] 0701[理学-数学] 

主　　题：QR algorithm deflation implicit shifts eigenvalues eigenvectors 

摘      要：Aggressive early deflation is a QR algorithm deflation strategy that takes advantage of matrix perturbations outside of the subdiagonal entries of the Hessenberg QR iterate. It identifies and deflates converged eigenvalues long before the classic small-subdiagonal strategy would. The new deflation strategy enhances the performance of conventional large-bulge multishift QR algorithms, but it is particularly effective in combination with the small-bulge multishift QR algorithm. The small-bulge multishift QR sweep with aggressive early deflation maintains a high rate of execution of floating point operations while significantly reducing the number of operations required.