This week, my professor stated the image of Mona Lisa below has undergone a horizontal shear and the way to model this shear mathematically in 2 dimensions is to use the following sort of matrix:
$$\begin{pmatrix}1 & a\\0 & 1\end{pmatrix},$$
where $a$ is the shear factor. It has a single eigenvector, namely 1, and all eigenvectors corresponding to this single eigenvector have the form
$$\begin{pmatrix}k\\0 \end{pmatrix},$$
where $k≠0$
My question is, how would this be modelled mathematically in 3 or more dimensions? Would the matrix increase to a 3x3 matrix, and so on? Also, would you have any textbook recommendations which cover this topic?
