Why $X^TX$ not always positive semidefinite using numpy.linalg.eig?
118417
Is $AA^T$ positive semidefinite?
30268
Positive definite matrix must be Hermitian
68132
Small positive eigenvalues found for a negative definite matrix
143634
Projecting a Non Negative Vector onto the Simplex
103087
What is the duality relationship between eigensystems of X X' vs X' X?
4443
Why is the determinant zero iff the column vectors are linearly dependent?
110271
Given a matrix with non-negative real entries, can you algebraically prove that it has a non-negative eigenvalue?
140078
Interpretation of eigenvectors of Hessian in context of local min/max/saddle?
88746
Positive definiteness of the matrix $A+B$
58476
Why can a matrix whose kth power is I be diagonalized?
59402
Comparing Eigenvalues of Positive Semidefinite Matrices
36775
Matrix semi-positive definite
153372
Characterization of positive definite matrix with principal minors
54386
What is the relationship between the spectrum of a matrix and its image under a polynomial function?
52260
Diagonalization and eigenvalues
100731
Positive operator has a positive spectrum?
117808
A real nxn matrix always has a real eigenvalue when n is odd