MathJax 多行公式

$\mathbf{\vec{T}}=\sum\limits_{r=1}^{R}{{{{\mathbf{\vec{H}}}}^{\left( r \right)}}\underset{2}{\mathop{\bullet }}\,}{{\mathbf{A}}^{\left( r \right)}}\underset{3}{\mathop{\bullet }}\,{{\mathbf{B}}^{\left( r \right)}}$

array：
$$ \begin{array}{*{20}{l}}
  {}&{{{{\mathbf{\vec H}}}^{\left( r \right)}} \in {\mathbb{C}^{I \times L \times P}}} \\
  {}&{{{\mathbf{A}}^{\left( r \right)}} \in {\mathbb{C}^{J \times L}}} \\
  {}&{{{\mathbf{B}}^{\left( r \right)}} \in {\mathbb{C}^{J \times L}}}
\end{array}$$

align：
\[\begin{align}
  & {{{\mathbf{\vec{H}}}}^{\left( r \right)}}\in {{\mathbb{C}}^{I\times L\times P}} \\
 & {{\mathbf{A}}^{\left( r \right)}}\in {{\mathbb{C}}^{J\times L}} \\
 & {{\mathbf{B}}^{\left( r \right)}}\in {{\mathbb{C}}^{J\times L}} \\
\end{align}\]

gathered：
\[\begin{gathered}
  {{{\mathbf{\vec H}}}^{\left( r \right)}} \in {\mathbb{C}^{I \times L \times P}} \\
  {{\mathbf{A}}^{\left( r \right)}} \in {\mathbb{C}^{J \times L}} \\
  {{\mathbf{B}}^{\left( r \right)}} \in {\mathbb{C}^{J \times L}} \\
\end{gathered} \]


\[\begin{gathered}
  {{{\mathbf{\vec H}}}^{\left( r \right)}} \in {\mathbb{R}^{I \times L \times P}} \hfill \\
  {{\mathbf{A}}^{\left( r \right)}} \in {\mathbb{Z}^{J \times L}} \hfill \\
  {{\mathbf{B}}^{\left( r \right)}} \in {\mathbb{C}^{J \times L}} \hfill \\
\end{gathered} \]