Latex Matrix Example

 \[  
 \begin{bmatrix}  
  X^1_1 & X^1_2 & \cdots & X^1_d \\  
  X^2_1 & X^2_2 & \cdots & X^2_d \\  
   \vdots & & & \\  
   X^N_1 & X^N_2 & \cdots & X^N_d    
 \end{bmatrix}  
 \]  

You can reference to the latex wiki page.