Branquinho, AmílcarFoulquié Moreno, AnaMañas Baena, Manuel Enrique2024-04-092024-04-092023-11-15Branquinho, A., Foulquié-Moreno, A., & Mañas, M. (2023). Positive bidiagonal factorization of tetradiagonal Hessenberg matrices. Linear Algebra and its Applications, 677, 132-160.0024-379510.1016/j.laa.2023.08.001https://hdl.handle.net/20.500.14352/1029052023 Acuerdos transformativos CRUERecently, a spectral Favard theorem was presented for bounded banded lower Hessenberg matrices that possess a positive bidiagonal factorization. The paper establishes conditions, expressed in terms of continued fractions, under which an oscillatory tetradiagonal Hessenberg matrix can have such a positive bidiagonal factorization. Oscillatory tetradiagonal Toeplitz matrices are examined as a case study of matrices that admit a positive bidiagonal factorization. Furthermore, the paper proves that oscillatory banded Hessenberg matrices are organized in rays, where the origin of the ray does not have a positive bidiagonal factorization, but all the interior points of the ray do have such a positive bidiagonal factorization.engAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/journal article1873-1856https://www.sciencedirect.com/science/article/pii/S0024379523003002open access51-72Banded Hessenberg matricesOscillatory matricesTotally nonnegative matricesFísica-Modelos matemáticos2212 Física Teórica