For a matrix AAA, if Av=λvAv = \lambda vAv=λv, what is true about ATA^TAT?
ATA^TAT has the same eigenvectors as AAA.
The characteristic polynomial of ATA^TAT is the same as AAA.
ATA^TAT has the same eigenvalues as AAA.
The sum of eigenvalues of ATA^TAT is different from AAA.