Plamen S. Koev Dopico, F. M., & Koev, P. (2008). Bidiagonal decompositions of oscillating systems of vectors. LINEAR ALGEBRA AND ITS APPLICATIONS, 428(11-12), 2536–2548. https://doi.org/10.1016/j.laa.2007.12.002 Canto, R., Koev, P., Ricarte, B., & Urbano, A. M. (2008). LDU FACTORIZATION OF NONSINGULAR TOTALLY NONPOSITIVE MATRICES. SIAM JOURNAL ON MATRIX ANALYSIS AND APPLICATIONS, 30(2), 777–782. https://doi.org/10.1137/060662897