Unstructured Perturbation
q
Problem: Given
M
Î
C
p
´
q
, find a smallest
D
Î
C
p
´
q
(no structure
imposed on
D
) in the sense of
such that
det(
I-M
D
)
=0.
q
It is easy to see that
q
q
q
with a smallest “destabilizing”
q
q
So
the largest singular value of
M
can be defined as