Hilbert space idempotents and involutions

被引：65

作者：

Buckholtz, D ^{[1
]}

机构：

[1] Univ Kentucky, Dept Math, Lexington, KY 40506 USA

来源：

PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY | 2000年 / 128卷 / 05期

关键词：

D O I：

10.1090/S0002-9939-99-05233-8

中图分类号：

O29 [应用数学];

学科分类号：

070104 ;

摘要：

Norms of idempotents, involutions, and the Hermitian and skew-Hermitian parts of involutions are shown to be elementary trigonometric functions of an angle between two subspaces of Hilbert space. When the spaces involved are nontrivial, the norm of a linear idempotent is the cosecant of the angle between its range and kernel; the norm of a linear involution is the cotangent of half the angle between the involution's eigenspaces.

引用

页码：1415 / 1418

页数：4