Source TeX:

C =G_2 (G_1A) = \begin{pmatrix} \sqrt 2 & \frac{1}{\sqrt{2}} & \frac{1}{\sqrt{2}} \\ 0 & \sqrt{\frac32} & \frac{1}{\sqrt{6}} \\ 0 & 0 & \frac{1}{\sqrt{3}}\\ 0 & 0 & 1 \end{pmatrix}.