P-matrix

In mathematics, a ${\displaystyle P}$-matrix is a complex square matrix with every principal minor > 0. A closely related class is that of ${\displaystyle P_{0}}$-matrices, which are the closure of the class of ${\displaystyle P}$-matrices, with every principal minor ${\displaystyle \geq }$ 0.

By a theorem of Kellogg, the eigenvalues of ${\displaystyle P}$- and ${\displaystyle P_{0}}$- matrices are bounded away from a wedge about the negative real axis as follows:

...
Wikipedia