- #1
- 996
- 5
If Q is an m x n (m > n) matrix with orthonormal columns, we know that [itex]Q^TQ = I[/itex] of dimension n x n. I have a question about [itex]QQ^T[/itex]. It is a symmetric m x m matrix but also appears to be singular. Why would it be singular? Probably something basic I've long since forgotten.