Block Numerical Range and Estimable Decomposition of Some Hyponormal Operators
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DOI: 10.1007/s11785-019-00967-2
Abstract: In this paper we investigate the block numerical range and the existences of estimable decompositions of bounded linear operators on a separable Hilbert space. By using spectral measure, we show that there exists an estimable… read more here.
Keywords: block numerical; estimable decomposition; hyponormal operators; numerical range ... See more keywords
Elliptical higher rank numerical range of some Toeplitz matrices
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DOI: 10.1016/j.laa.2018.03.024
Abstract: Abstract The higher rank numerical range is described for a class of matrices which happen to be unitarily reducible to direct sums of (at most) 2-by-2 blocks. In particular, conditions are established under which tridiagonal… read more here.
Keywords: rank numerical; rank; higher rank; numerical range ... See more keywords
Matrix powers with circular numerical range
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DOI: 10.1016/j.laa.2020.05.039
Abstract: Abstract Let K 2 = [ 0 2 0 0 ] , K n be the n × n weighted shift matrix with weights 2 , 1 , … , 1 ︸ n − 3… read more here.
Keywords: circular numerical; matrix powers; powers circular; numerical range ... See more keywords
Quaternionic numerical range of complex matrices
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DOI: 10.1016/j.laa.2021.02.030
Abstract: The paper explores further the computation of the quaternionic numerical range of a complex matrix. We prove a modified version of a conjecture by So and Tompson. Specifically, we show that the shape of the… read more here.
Keywords: complex matrix; numerical range; quaternionic numerical; range complex ... See more keywords
Eigenvalue inequalities for positive block matrices with the inradius of the numerical range
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DOI: 10.1142/s0129167x22500094
Abstract: We prove the operator norm inequality, for a positive matrix partitioned into four blocks in [Formula: see text], [Formula: see text] where [Formula: see text] is the diameter of the largest possible disc in the… read more here.
Keywords: formula see; eigenvalue inequalities; see text; numerical range ... See more keywords
Approximation of the block numerical range of block operator matrices
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DOI: 10.2298/fil1912877y
Abstract: In this paper we obtain an approximation of the block numerical range of bounded and unbounded block operator matrices by projection methods. read more here.
Keywords: block numerical; block; operator matrices; block operator ... See more keywords