# P-matrix

### From Glossary

A square matrix with all of its principal minors positive. This includes all symmetric, positive definite matrices. Here is an example of a P-matrix that is not positive definite:

The principal minors are positive, but
The significance of this class is in the theorem:

*The linear complementarity problem, defined by has a unique solution for each q in R*^{n}if, and only if, is a P-matrix.