 Negative definiteness

Negative definiteness is a concept from linear algebra and functional analysis, particularly in the context of matrices and quadratic forms. A matrix \( A \) is said to be negative definite if it satisfies the following conditions: 1. **Square Matrix**: The matrix \( A \) is a square matrix (i.e., it has the same number of rows and columns). 2. **Negative Eigenvalues**: All eigenvalues of the matrix \( A \) are negative.