Conditions for the generalized numerical range to be real (Q1070010)
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scientific article; zbMATH DE number 3933240
| Language | Label | Description | Also known as |
|---|---|---|---|
| English | Conditions for the generalized numerical range to be real |
scientific article; zbMATH DE number 3933240 |
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Conditions for the generalized numerical range to be real (English)
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1985
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Let C and A be given \(n\times n\) matrices. The classical numerical range \(W(CU^*AU)\) is contained in the real axis for all unitary U iff at least one of C and A is scalar and their product is Hermitian. The authors also investigate two generalized numerical ranges and describe the situations where these are real, or contained in a line parallel to the real axis.
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numerical range
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Hermitian
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