How To Study As A Mathematics Major
《How To Study As A Mathematics Major》 · 第 164 页 · Section 3.1「The Jordan canonical form theorem」，Definition 3.1.1
A Jordan block $J_k(\lambda)$ is a $k$-by-$k$ upper triangular matrix of the form $J_k(\lambda)=\begin{pmatrix}\lambda&1&&0\\&\lambda&\ddots&\\&&\ddots&1\\0&&&\lambda\end{pmatrix}$. The scalar $\lambda$ appears $k$ times on the main diagonal; if $k>1$, there are $k-1$ entries “$+1$” in the superdiagonal; all other entries are zero.