“…The effect of structure-preserving perturbations of the matrix entries has been analyzed in the context of linear systems (see, e.g., [37,15,31,32]) as well as for structured eigenproblems. Measures of structured eigenvalue sensitivity include both structured pseudospectra (see, e.g., [11,30,7,17,3,25]) and structured condition numbers, introduced by Tisseur [35]. The latter measures have been investigated, e.g., in [18,22,24,2] and, recently, applied to network analysis [28,10].…”