Hi,

I couldn't find a Jordan-basis for this matrix:

$\displaystyle A=\begin{bmatrix}1 & 0 & 3 & 0\\ 0 & 1 & 5 & 0\\ 0 & 0 & 1 &0\\0 & 0 & 0 &1\end{bmatrix}$

I have found an eigenvector: v1=[3 5 0 0] then an other vector v2 for (A-I)v2=v1, then I tried to compute (A-I)v3=v2 but that was inconsistent so I think I need 2 other eigenvectors, but I don't know how to find them.

Thanks for your help!