Abstract
In early studies of Hilbert space (by Hilbert, Hellinger, Toeplitz, and others) the objects of chief interest were quadratic forms. Nowadays they play a secondary role. First comes an operator A on a Hilbert space H, and then, apparently as an afterthought, comes the numerical-valued function f ↦ (Af, f) on H. This is not to say that the quadratic point of view is dead; it still suggests questions that are interesting with answers that can be useful.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
Rights and permissions
Copyright information
© 1982 Springer-Verlag New York Inc
About this chapter
Cite this chapter
Halmos, P.R. (1982). Numerical Range. In: A Hilbert Space Problem Book. Graduate Texts in Mathematics, vol 19. Springer, New York, NY. https://doi.org/10.1007/978-1-4684-9330-6_22
Download citation
DOI: https://doi.org/10.1007/978-1-4684-9330-6_22
Publisher Name: Springer, New York, NY
Print ISBN: 978-1-4684-9332-0
Online ISBN: 978-1-4684-9330-6
eBook Packages: Springer Book Archive