Why do the eigenvalues of $A^TB$ equal the nonzero eigenvalues of $AB^T$?
88349
Are the eigenvalues of $AB$ equal to the eigenvalues of $BA$? (Citation needed!)
157246
Adjoint matrix eigenvalues and eigenvectors
6514
Prove $T$ has at most two distinct eigenvalues
61274
If $AA^T$ is the zero matrix, then $A$ is the zero matrix
118417
Is $AA^T$ positive semidefinite?
99585
Do the non-zero eigenvalues of AB and BA have the same algebraic multiplicity (for AB and BA not square)?
52260
Diagonalization and eigenvalues
28584
Eigenvalues and eigenspaces of AB
3150
Is there an intuitive interpretation of $A^TA$ for a data matrix $A$?
75536
every eigenvalue of $T$ has only one corresponding eigenvector up to a scalar multiplication
129977
Prove that $\lambda_1^2$, $\lambda_1\lambda_2$ and $\lambda_2^2$ are eigenvalues of matrix $A$
110086
Let $A$ be an $m \times n$ matrix. Show $A^TA$ and $AA^T$ have the same eigenvalues
81868
How to prove $\operatorname{Tr}(AB) = \operatorname{Tr}(BA)$?
151332
If $A,B$ have eigenvalues $\pm1$, what can I say about the eigenvalues of $AB,BA$?
106024
The eigenvalues and corresponding eigenvectors for the matrix
45527
Do real matrices always have real eigenvalues?
127799
Eigenvalues of symmetric matrices are real without (!) complex numbers