If all the eigenvalues of a real matrix have real parts, then to an arbitrary negative definite quadratic form with there corresponds a positive definite quadratic form such that if one takes
then and satisfy
If all the eigenvalues of a real matrix have real parts, then to an arbitrary negative definite quadratic form with there corresponds a positive definite quadratic form such that if one takes
then and satisfy
Weisstein, Eric W. "Lyapunov's Second Theorem." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/LyapunovsSecondTheorem.html