# Schur Decomposition Any matrix $A \in \mathbb{C}^{n \times n}$ has a Schur decomposition $A=Q T Q^*$, where $Q$ is unitary and $T$ is upper triangular. The eigenvalues of $A$ appear on the diagonal of $T$. For each $k$, the leading $k$ columns of $Q$ span an invariant subspace of $A$. --- ## References