<<< native
[ EDelimited
    "["
    "]"
    [ Right
        (EArray
           [ AlignCenter , AlignCenter ]
           [ [ [ EFraction
                   DisplayFrac
                   (EGrouped
                      [ ESymbol Ord "\8706" , ESub (EIdentifier "x") (ENumber "1") ])
                   (EGrouped
                      [ ESymbol Ord "\8706" , ESub (EIdentifier "y") (ENumber "1") ])
               ]
             , [ EFraction
                   DisplayFrac
                   (EGrouped
                      [ ESymbol Ord "\8706" , ESub (EIdentifier "x") (ENumber "2") ])
                   (EGrouped
                      [ ESymbol Ord "\8706" , ESub (EIdentifier "y") (ENumber "1") ])
               ]
             ]
           , [ [ ESpace (2 % 9) ] ]
           , [ [ EFraction
                   DisplayFrac
                   (EGrouped
                      [ ESymbol Ord "\8706" , ESub (EIdentifier "x") (ENumber "1") ])
                   (EGrouped
                      [ ESymbol Ord "\8706" , ESub (EIdentifier "y") (ENumber "2") ])
               ]
             , [ EFraction
                   DisplayFrac
                   (EGrouped
                      [ ESymbol Ord "\8706" , ESub (EIdentifier "x") (ENumber "2") ])
                   (EGrouped
                      [ ESymbol Ord "\8706" , ESub (EIdentifier "y") (ENumber "2") ])
               ]
             ]
           ])
    ]
, EDelimited
    "("
    ")"
    [ Right
        (EArray
           [ AlignCenter , AlignCenter ]
           [ [ [ ENumber "1" ] , [ ENumber "2" ] ]
           , [ [ ENumber "3" ] , [ ENumber "4" ] ]
           ])
    ]
, EDelimited
    "{"
    "}"
    [ Right
        (EArray
           [ AlignCenter , AlignCenter ]
           [ [ [ ENumber "1" ] , [ ENumber "2" ] ]
           , [ [ ENumber "3" ] , [ ENumber "4" ] ]
           ])
    ]
, EDelimited
    "\8739"
    "\8739"
    [ Right
        (EArray
           [ AlignCenter , AlignCenter ]
           [ [ [ ENumber "1" ] , [ ENumber "2" ] ]
           , [ [ ENumber "3" ] , [ ENumber "4" ] ]
           ])
    ]
, EDelimited
    "\8741"
    "\8741"
    [ Right
        (EArray
           [ AlignCenter , AlignCenter ]
           [ [ [ ENumber "1" ] , [ ENumber "2" ] ]
           , [ [ ENumber "3" ] , [ ENumber "4" ] ]
           ])
    ]
]
>>> tex
\begin{bmatrix}
\dfrac{\partial x_{1}}{\partial y_{1}} & \dfrac{\partial x_{2}}{\partial y_{1}} \\
\  \\
\dfrac{\partial x_{1}}{\partial y_{2}} & \dfrac{\partial x_{2}}{\partial y_{2}}
\end{bmatrix}\begin{pmatrix}
1 & 2 \\
3 & 4
\end{pmatrix}\begin{Bmatrix}
1 & 2 \\
3 & 4
\end{Bmatrix}\begin{vmatrix}
1 & 2 \\
3 & 4
\end{vmatrix}\begin{Vmatrix}
1 & 2 \\
3 & 4
\end{Vmatrix}