Source TeX:

G_1A = \begin{pmatrix} \sqrt 2 & \frac{1}{\sqrt{2}} & \frac{1}{\sqrt{2}} \\ 0 & -\frac{1}{\sqrt{2}} & -\frac{1}{\sqrt{2}} \\ 0 & 1 & 0 \\ 0 &0& 1\\ \end{pmatrix},