Numerical Range

  • Paul R. Halmos
Part of the Graduate Texts in Mathematics book series (GTM, volume 19)


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.


Convex Hull Compact Operator Quadratic Point Numerical Range Cube Root 


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Copyright information

© Springer-Verlag New York Inc 1982

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  • Paul R. Halmos

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