SEVERAL NEW RESULTS ON THE POLAR DECOMPOSITION AND GENERALIZED POLAR DECOMPOSITION
关于极分解和广义极分解的一些新结果

This paper concerns the polar decomposition and generalized polar decomposition.The approximation theorem proved by Sun and Chen is extended from Frobenius norm to any unitarily invariant norm. A new explicit representation of the subunitary polar factor is obtained.By using this new expression,we derive a perturbation bound for the subunitary polar factor for any unitarily invariant norm.Finally,numerical computation is discussed.