Below you can access the Matlab routines to compute the pseudospectral abscissa of a large-scale matrix-valued 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.

1. Download the routines (Last update: October 10, 2016)
   
2. Sample calls
   

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.

• K. Meerbergen, E. Mengi, W. Michiels and R. Van Beeumen. Computation of Pseudospectral Abscissa for Large Scale Nonlinear Eigenvalue Problems. Submitted to IMA J. Numerical Analysis.

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.