Question

How do I enter a matrix in the equation editor?

Answer 1

I don't even bother with the editor. It's a little tricky, but it's called LaTeX. The first thing you want to do is enclose everything in between \ [ and \ ] (no spaces).

Answer 2

Next, do you want big parentheses around the matrix ( ) or big square brackets [ ]?

Answer 3

If you want ( ) you start each matrix with \left( and end it with \right). Alternately, you would use \left[ and \right]

Answer 4

To get the actual matrix, we use

\begin{array}{cccc}

where the number of c's we use is the same as the number of columns.

Answer 5

then in each row,

a11&a12&a13\\ and so on

the last row doesn't use \\

then at the end we use \end{array}

Answer 6

So for the matrix

\[\left[\begin{array}{cccc}
a_{11}&a_{12}&\ldots&a_{1n}\\
a_{21}&a_{22}&\ldots&a_{2n}\\
\vdots&\vdots&\ddots&\vdots\\
a_{n1}&a_{n2}&\ldots&a_{nn}
\end{array}\right]\]

I use

\ [\left[\ begin{array}{cccc}
a_{11}&a_{12}&\ldots&a_{1n}\\
a_{21}&a_{22}&\ldots&a_{2n}\\
\vdots&\vdots&\ddots&\vdots\\
a_{n1}&a_{n2}&\ldots&a_{nn}
\end{array}\right]\]

Where you take out the the spaces after the first and third \

Answer 7

testing...

\[ \left[ \begin{array}{cc} a & b \\ c & d \end{array} \right] \]

Nice. Thanks!

Answer 8

You're welcome.

Answer 9

Glad to help.

Answer 10

wait, why's that "a" not line the others?

Answer 11

I don't know. It seems to do that on the first one for some reason.

Answer 12

Huh. and it's not doing it in the preview. weird.

Answer 13

By the way, FYI -- you can leave off the \ on most LaTeX commands *in the editor*. Right now, that doesn't work in the reply box directly, though we *may* add that.