Software to Compute Pseudospectral Abscissa
Below you can access the Matlab routines to compute the pseudospectral abscissa of a largescale matrixvalued function. The main routine to call is psa_subs_init. See the sample calls file before using the routines. To learn the details of the input and output arguments, type help psa_subs_init in the Matlab command window.
These routines can specifically be used to compute the pseudospectral abscissa of

a large matrix,

a matrix polynomial,

a delay eigenvalue problem,
and are implementations of the approach described in the following paper.
The figure on the left above concerns a delay example, the exact data is available here. The figure on the right concerns the butterfly example, which is a quartic matrix polynomial available in the collection NLEVP.