ON THE INDEX OF BLOCK UPPER-TRIANGULAR MATRICES

Authors
BRU R CLIMENT JJ NEUMANN M
Citation
R. Bru et al., ON THE INDEX OF BLOCK UPPER-TRIANGULAR MATRICES, SIAM journal on matrix analysis and applications, 16(2), 1995, pp. 436-447
Citations number
8
Categorie Soggetti
Mathematics,Mathematics
Journal title
SIAM journal on matrix analysis and applications → ACNP
ISSN journal
08954798
Volume
16
Issue
2
Year of publication
1995
Pages
436 - 447
Database
ISI
SICI code
0895-4798(1995)16:2<436:OTIOBU>2.0.ZU;2-N
Abstract
Let M be an upper block triangular matrix with A and B singular diagon al blocks. It is known that max{index(A), index(B)} less than or equal to index(M) less than or equal to index(A) + index(B). Recently, a ne cessary and sufficient condition has been given so that index(M) = ind ex(A)S-index(B). In this paper we find various characterizations for i ndex(M) to take any specific values between max{ index(il), index(B)} and index(A) + index(B) which generalize previous results.