The definition material radius of stability

In this work is looking off sufficiently classes of matrixes stability on Vagevskiy, i.e. stability matrixes $P$ for that symmetrical matrix $P+P^{T}$ also stability. For this family of matrixes is describes, that they material radius of stability is appears smaller own number of matrix – $(P+P^{T})/2$. This result is allows to define material raduis of stability «over stability» matrixes, i.e. they ia appears the matrixes stability on Vashevskiy.