Generalized Hessenberg matrices Original Research Article

We define and study generalized Hessenberg matrices, i.e. square matrices which have subdiagonal rank one. Here, subdiagonal rank means the maximum order of a nonsingular submatrix all of whose entries are in the subdiagonal part. We prove that the property of being generalized Hessenberg matrix is preserved by post- and premultiplication by a nonsingular upper triangular matrix, by inversion (for invertible matrices), etc. We also study a special kind of generalized Hessenberg matrices.