How to write an m*n matrix in latex

Question

I tried using the below code.But it works only for 2*2 matrix.

            \[
         M=
            \left[ {\begin{array}{cc}
             1 & 2 \\
             3 & 4 \\
                \end{array} } \right]
        \]

Now this doesn't work for me.

\[
         M=
            \left[ {\begin{array}{cc}
             1 & 2 & 3 & 4 & 5\\
             3 & 4 & 5 & 6 & 7\\
                \end{array} } \right]
        \]

Answer 1

In the example you have, you need the opening line to be

 \left[ {\begin{array}{ccccc}

rather than

 \left[ {\begin{array}{cc}

When you start with just two 'c's, you're telling it the matrix only has two columns (and that you want them centered). Then it breaks when you give it data for 5 columns.

Answer 2

A better way to do it, is the TheHe meantioned, with amsmath:

\documentclass{article}
\usepackage{amsmath}
\begin{document}

\[
M=
  \begin{bmatrix}
    1 & 2 & 3 & 4 & 5\\
    3 & 4 & 5 & 6 & 7\\
  \end{bmatrix}
\]

\end{document}

The bmatrix environment will give you [] braces. () braces are also very common. They are created with the pmatrix environment. To include a matrix inline, you can write:

$M = \left\[ \begin{smallmatrix} 1 & 2 \\ 3 & 4 \end{smallmatrix} \right\]$

Answer 3

if you use the amsmath-package, you can chose out of a lot of matrices like pmatrix or bmatrix...

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