The dynamics of coupling between spectrum and resolvent under epsilon-pertu
bations of operator and matrix spectra ave studied both theoretically and n
umerically. The phenomenon of non-trivial pseudospectra encountered in thes
e dynamics is treated by relating information in the complex plane to the b
ehaviour of operators and matrices. On a number of numerical results we sho
w how an intrinsic blend of theory with symbolic and numerical computations
can be used effectively for the analysis of spectral problems arising from
engineering applications.