Why are the eigenvectors of $A$ orthogonal when $AA^T=A^T A$?
60723
Prove that if $A$ is normal, then eigenvectors corresponding to distinct eigenvalues are necessarily orthogonal (alternative proof)
134306
If $A$ is a normal matrix such that $A^{247} = A^{246}$, how to prove that $A$ is an orthogonal projection?
52260
Diagonalization and eigenvalues
133609
orthonormal system in a Hilbert space
62030
$A^2=A^*A$. Why is matrix $A$ Hermitian?
149219
If $A$ is a non-square matrix with orthonormal columns, what is $A^+$?
29408
Get Eigensystem to return orthogonal eigenvectors for Hermitian matrix
109471
The eigenvectors of the transpose operator
143793
If $A$ is symmetric, then the matrix exponential $e^{A}$ is positive definite
141628
How did the equation $|A- \lambda I| = 0$ came for finding Eigen values of a Matrix
50384
A matrix and its transpose have the same set of eigenvalues/other version: $A$ and $A^T$ have the same spectrum
50010
Is this how eigenvalues of some matrix $A$ are related to the inverse of $A$?
86919
When (and more importantly, why) does $AA^T$ have an inverse?
90757
$T$ self-adjoint on Hilbert space $H$, $T^n=T^{n+1}$ will $T$ be an orthogonal projection operator?
69980
Proving that if $A$ is an $n\times n$ orthogonal matrix, then $\det(A) = \pm1$
88975
I need an intuitive explanation of eigenvalues and eigenvectors
70245
Why is the eigenvector in PCA taken to be unit norm?