New perturbation bounds in unitarily invariant norms for subunitary polar factors

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Lei Zhu
Wei-wei Xu
Hao Liu
Li-juan Ma


Let $A\in\mathbb{C}^{m \times n}$ have generalized polar decomposition $A = QH$ with $Q$ subunitary and $H$ positive semidefinite. Absolute and relative perturbation bounds are derived for the subunitary polar factor $Q$ in unitarily invariant norms and in $Q$-norms, that extend and improve existing bounds.

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