The main diagonal of a permutation matrix

By counting 1’s in the “right half” of 2w consecutive rows, we locate the main diagonal of any doubly infinite permutation matrix with bandwidth w. Then the matrix can be correctly centered and factored into block-diagonal permutation matrices. Part II of the paper discusses the same questions for...

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Bibliographic Details
Main Authors: Lindner, Marko, Strang, Gilbert
Other Authors: Massachusetts Institute of Technology. Department of Mathematics
Format: Article
Language:en_US
Published: Elsevier 2015
Online Access:http://hdl.handle.net/1721.1/99450
https://orcid.org/0000-0001-7473-9287
Description
Summary:By counting 1’s in the “right half” of 2w consecutive rows, we locate the main diagonal of any doubly infinite permutation matrix with bandwidth w. Then the matrix can be correctly centered and factored into block-diagonal permutation matrices. Part II of the paper discusses the same questions for the much larger class of band-dominated matrices. The main diagonal is determined by the Fredholm index of a singly infinite submatrix. Thus the main diagonal is determined “at infinity” in general, but from only 2w rows for banded permutations.