# How to extract a subspace

by weetabixharry
Tags: extract, subspace
Of course, this can be simplified as:$$\begin{eqnarray*} \mathbf{A}_{2D} &=&\mathbf{E}_{2}^{+}\mathbf{A} \\ &=&\left( \mathbf{E}_{2}^{T}\mathbf{E}_{2}\right)^{-1} \mathbf{E}_{2}^{T}\mathbf{A% } \\ &=&\mathbf{E}_{2}^{T}\mathbf{A} \end{eqnarray*}$$