Pseudospectra, stability radii and their relationship with backward error for structured nonlinear eigenvlaue problems

This paper discusses pseudospectra and stability radii for structured nonlinear matrix functions, such as Hermitian, skew-Hermitian, H-even, H-odd, complex symmetric, and complex skew-symmetric. To compute pseudospectra and stability radii, eigenvalue backward error is required. Hence, we initially present the structured eigenvalue backward error. Subsequently, we compute the structured pseudospectra using the obtained results for the eigenvalue backward error of a class of structured nonlinear matrix functions. Finally, we discuss the stability radii of the above-structured problems arising in different applications. The paper also generalizes the results on the eigenvalue backward error of matrix polynomials in the literature for the above structures.