Kharitonov
polynomials are special polynomials that have constant values for their
coefficients and are associated to a parametric polynomial.
It can be shown that if all the Kharitonov polynomials have
the real parts of their roots of the same sign, then all the
polynomials in the set will have the real part of their roots of the same
sign.
For a polynomial
the four Kharitonov polynomials are: