A stronger version of matrix convexity as applied to functions of Hermitian matrices

<p/> <p>A stronger version of matrix convexity, called hyperconvexity is introduced. It is shown that the function <inline-formula><graphic file="1029-242X-1999-260365-i1.gif"/></inline-formula> is hyperconvex on the set of Hermitian matrices <inline-formul...

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Bibliographic Details
Main Authors: Kagan Abram, Smith Paul J
Format: Article
Language:English
Published: SpringerOpen 1999-01-01
Series:Journal of Inequalities and Applications
Subjects:
Online Access:http://www.journalofinequalitiesandapplications.com/content/3/260365
Description
Summary:<p/> <p>A stronger version of matrix convexity, called hyperconvexity is introduced. It is shown that the function <inline-formula><graphic file="1029-242X-1999-260365-i1.gif"/></inline-formula> is hyperconvex on the set of Hermitian matrices <inline-formula><graphic file="1029-242X-1999-260365-i2.gif"/></inline-formula> and <inline-formula><graphic file="1029-242X-1999-260365-i3.gif"/></inline-formula> is hyperconvex on the set of positive definite Hermitian matrices. The new concept makes it possible to consider weighted averages of matrices of different orders. Proofs use properties of the Fisher information matrix, a fundamental concept of mathematical statistics.</p>
ISSN:1025-5834
1029-242X