Abstract
Let H be a field with Q⊆H⊆C, and let p(λ) be a polynomial in H[λ], and let A∈Hn×n be nonderogatory. In this paper we consider the problem of finding a solution X∈Hn×n to p(X)=A. A necessary condition for this to be possible is already known from a paper by M.P. Drazin: Exact rational solutions of the matrix equation A=p(X) by linearization. Under an additional condition we provide an explicit construction of such solutions. The similarities and differences with the derogatory case will be discussed as well. One of the tools needed in the paper is a new canonical form, which may be of independent interest. It combines elements of the rational canonical form with elements of the Jordan canonical form.
Original language | English |
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Pages (from-to) | 107-138 |
Number of pages | 32 |
Journal | Linear Algebra and its Applications |
Volume | 665 |
Early online date | 3 Feb 2023 |
DOIs | |
Publication status | Published - 15 May 2023 |
Bibliographical note
Funding Information:This work is based on research supported in part by the DSI-NRF Centre of Excellence in Mathematical and Statistical Sciences (CoE-MaSS) and in part by the National Research Foundation of South Africa (Grant Numbers 145688 and 2022-012-ALG-ILAS ). Opinions expressed and conclusions arrived at are those of the authors and are not necessarily to be attributed to the CoE-MaSS.
Publisher Copyright:
© 2023 The Author(s)
Funding
This work is based on research supported in part by the DSI-NRF Centre of Excellence in Mathematical and Statistical Sciences (CoE-MaSS) and in part by the National Research Foundation of South Africa (Grant Numbers 145688 and 2022-012-ALG-ILAS ). Opinions expressed and conclusions arrived at are those of the authors and are not necessarily to be attributed to the CoE-MaSS.
Keywords
- Canonical forms
- Companion matrices
- Linear matrix equations
- Matrices over field extensions of the rationals
- Nonderogatory matrices
- Solutions of polynomial matrix equations