TeX source:

\mathbf{A}_{\mathrm{O}_{0}}\left[\mathrm{O}_{0}, \mathrm{O}_{i}\right]=\mathbf{A}\left[\mathrm{O}_{0}, \mathrm{O}_{i}\right] \times \mathbf{A}\left[\mathrm{O}_{0}, \mathrm{O}_{i}\right]^{\mathrm{T}}