Abstract
The concept of the bi-dagger matrix was introduced by Hartwig and Spindelböck [8]. In this paper, we provide some new characterizations of bi-dagger matrices. We prove that the index of a bi-dagger matrix is less than or equal to 2 and that a matrix is bi-dagger if and only if it is i-EP, and its index is less than or equal to 2. Specifically, a matrix is bi-dagger if and only if it commutes with its B-T inverse. Finally, we consider Problem 5 in [8] and establish conditions under which a bi-dagger matrix implies bi-normality.
| Original language | English |
|---|---|
| Pages (from-to) | 4431-4439 |
| Number of pages | 9 |
| Journal | Filomat |
| Volume | 39 |
| Issue number | 13 |
| DOIs | |
| Publication status | Published - 2025 |