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 the following doesn't work for me:

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

It should work with any size. Can you be more specific about what happens when it "doesn't work"? And give an example of input that doesn't give the output you want? — , Sep 01 '12 at 00:00
General question (instead of debugging question): math mode - How to add a matrix to a LaTeX document - TeX - LaTeX Stack Exchange — user202729, Feb 08 '23 at 17:11

score 93 · Answer 1 · edited Apr 17 '15 at 10:48

93

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

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

edited Apr 17 '15 at 10:48

egreg

1,121,712

answered Sep 04 '12 at 06:20

bodo

6,228

1

In mathtools we also have bsmallmatrix environment. – percusse Sep 16 '14 at 14:01
I don't like it, it only has one line! – Tomáš Zato Feb 22 '15 at 13:22
He wrote '' instead of '\'. I'll edit that. – Astrinus Apr 17 '15 at 10:15
1

@Astrinus: Thank you. Actually this was not my mistake: http://meta.tex.stackexchange.com/questions/5978/something-messed-with-my-answers-backslashes-and-newlines. I hope this is fixed. – bodo Apr 17 '15 at 11:26

score 43 · Accepted Answer · edited Oct 27 '13 at 17:48

43

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 cs, 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.

edited Oct 27 '13 at 17:48

Svend Tveskæg

31,033

answered Sep 01 '12 at 00:21

5

@strpeter that's no reason to downvote, it's a valid answer – osvein Oct 29 '18 at 00:15

score 14 · Answer 3 · edited Oct 27 '13 at 17:47

14

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

Check out this list at Wikibooks.

edited Oct 27 '13 at 17:47

Svend Tveskæg

31,033

answered Sep 01 '12 at 00:03

Thanks you so much – Denis Jan 17 '20 at 10:10

score 11 · Answer 4 · edited Nov 30 '16 at 15:32

Using the pmatrix (p for parentheses) or bmatrix (b for brackets) environments as suggested above, also yields much better spacing than does array with \left( and \right) (for parentheses) or \left[ and \right] (for brackets). With array, the space between the parenthesis or bracket and the numbers is too large. You can see it for yourself comparing the results of this code:

\begin{equation}
R^2 = 
\left({\begin{array}{cc} c & s \end{array}}\right)
\left(\begin{array}{cc} 1 & 0\\ 0 & 1 \end{array}\right)
\left(\begin{array}{c} c \\ s \end{array}\right) 
= c^2 + s^2
\end{equation}

\begin{equation}
R^2 = 
\begin{pmatrix} c & s \end{pmatrix} 
\begin{pmatrix} 1 & 0\\ 0 & 1 \end{pmatrix}
\begin{pmatrix} c \\ s \end{pmatrix} 
= c^2 + s^2
\end{equation}

That outputs the following:

score 0 · Answer 5 · answered Apr 03 '20 at 10:34

0

It will not work because you have declared 2 columns (cc). Number of columns in your case should be 4, i.e., cccc. Then it will work.

answered Apr 03 '20 at 10:34

Vaman Kulkarni

123

4

Please. add MWE, that OP will be able simple test your (correct) solution. – Zarko Apr 03 '20 at 11:17

How to write an m⨉n matrix in LaTeX?

5 Answers5

Linked