Abstract
The Fiedler matrices are a large class of companion matrices that include the well-known Frobenius companion matrix. The Fiedler matrices are part of a larger class of companion matrices that can be characterized by a Hessenberg form. We demonstrate that the Hessenberg form of the Fiedler companion matrices provides a straight-forward way to compare the condition numbers of these matrices. We also show that there are other companion matrices which can provide a much smaller condition number than any Fiedler companion matrix. We finish by exploring the condition number of a class of matrices obtained from perturbing a Frobenius companion matrix while preserving the characteristic polynomial.
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Research of Vander Meulen was supported in part by NSERC Discovery Grant No. 2022-05137. Research of Van Tuyl was supported in part by NSERC Discovery Grant No. 2019-05412. Research of Voskamp was supported in part by NSERC USRA 504279.
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Cox, M., Vander Meulen, K.N., Van Tuyl, A. et al. Condition numbers of Hessenberg companion matrices. Czech Math J 74, 191–209 (2024). https://doi.org/10.21136/CMJ.2024.0060-23
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DOI: https://doi.org/10.21136/CMJ.2024.0060-23