## 2012.30: Triangularizing Quadratic Matrix Polynomials

2012.30:
Françoise Tisseur and Ion Zaballa
(2012)
*Triangularizing Quadratic Matrix Polynomials.*

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## Abstract

We show that any regular quadratic matrix polynomial can be reduced to an upper triangular quadratic matrix polynomial over the complex numbers preserving the finite and infinite elementary divisors. We characterize the real quadratic matrix polynomials that are triangularizable over the real numbers and show that those that are not triangularizable over the real numbers are quasi-triangularizable with diagonal blocks of sizes $1\times 1$ and $2 \times 2$. We also derive complex and real Schur-like theorems for linearizations of quadratic matrix polynomials with nonsingular leading coefficients. In particular, we show that for any monic linearization $\l I+A$ of an $n\times n$ quadratic matrix polynomial, there exists a nonsingular matrix defined in terms of $n$ orthonormal vectors that transforms $A$ to a companion linearization of a (quasi)-triangular quadratic matrix polynomial. This provides the foundation for designing numerical algorithms for the reduction of quadratic matrix polynomials to upper (quasi)-triangular form.

Item Type: | MIMS Preprint |
---|---|

Subjects: | MSC 2000 > 15 Linear and multilinear algebra; matrix theory MSC 2000 > 65 Numerical analysis |

MIMS number: | 2012.30 |

Deposited By: | Dr Françoise Tisseur |

Deposited On: | 24 February 2012 |

### Available Versions of this Item

- Triangularizing Quadratic Matrix Polynomials (deposited 08 November 2013)
- Triangularizing Quadratic Matrix Polynomials (deposited 20 August 2012)
- Triangularizing Quadratic Matrix Polynomials (deposited 27 February 2012)
- Triangularizing Quadratic Matrix Polynomials (deposited 24 February 2012)
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