Why is the precision matrix not positive definite?
109090
Inverting non positive definite covariance matrix
81719
Very different results from evaluating same expression with different precisions
145396
Symmetric Matrix , Eigenvectors are not orthogonal to the same eigenvalue.
119662
understanding projection matrices
107285
Why does a positively correlated variable have a negative coefficient in a multiple regression?
10366
Why do we not include $c$ in the computation of the definite integral?
156868
Why is finding $M$ eigenvectors on smaller matrix valid?
34036
Positive correlation and negative regressor coefficient sign
86623
Why is $B^TB+\lambda\Omega$ positive definite?
158205
If $A+A^T$ is negative definite, then the eigenvalues of $A$ have negative real parts?
43277
Confused by (apparent) inconsistent precision
51834
Positivity of a determinant
67686
Square root of Positive Definite Matrix
24132
Why does Gaussian elimination not preserve similarity of a matrix?
46308
Simultaneous diagonlisation of two quadratic forms, one of which is positive definite
30268
Positive definite matrix must be Hermitian
12868
Is the product of symmetric positive semidefinite matrices positive definite?