# How to have matrices side by side in latex?

I'm new to latex and all of my matrices seem to be created on new lines, I can't seem to put them side by side. Here is what I am doing to make a matrix (with the 2d identity matrix as an example):

$\left( \begin{array}{cc} 1 & 0 \\ 0 & 1 \end{array} \right)$


Am I making it wrong? How can I place a second matrix directly beside this, as you would when doing matrix mathematics? Thanks

Don't enclose each array with $...$; instead, put all the arrays that you want together within one set of delimeters. Like this:

$\left( \begin{array}{cc} 1 & 0 \\ 0 & 1 \end{array} \right) % \left( \begin{array}{cc} 1 & 0 \\ 0 & 1 \end{array} \right)$


You should read the mathmode documentation. It should be part of your TeX Distribution, and has lots of examples to follow.

• This makes sense. However, does this still handle things like [Matrix][vector] = [vector] all one one line?
– user3231
Jan 29 '11 at 20:49
• @bbel Sure. As long as they will fit on the same line, you can just put them one after another like this (no blank lines in between which is why I separated the two matrices in my example with a % (comment character)). Jan 29 '11 at 20:52

This is slightly tangential, but you might find it convenient to use the pmatrix environment (defined in amsmath.sty)

$\begin{pmatrix} 1 & 0 \\ 0 & e^{i\pi/k} \end{pmatrix} \begin{pmatrix} u \\ v \end{pmatrix} = \begin{pmatrix} u \\ -v \end{pmatrix}$


The idea is to enclose both matrices in one block i.e.  see this example

$\begin{bmatrix} a & b \\ c & d \end{bmatrix} = \begin{bmatrix} 8 & 1 \\ 7 & 6 \end{bmatrix}$


It will be something like:

– Werner
Oct 19 '16 at 4:27

like this

$\left( \begin{array}{cc} 1 & 0 \\ 0 & 1 \end{array} \right) \times \left( \begin{array}{cc} 1 & 0 \\ 0 & 1 \end{array} \right) =\left( \begin{array}{cc} 1 & 0 \\ 0 & 1 \end{array} \right)$


You need to place the matrices inside the math environment

• Inside the math environment by surrounding them with the dollar sign operator? Because that gives me errors in itself..
– user3231
Jan 29 '11 at 20:45
• $..$ is a math environment When you use this environment the math expression is written on a single line. Like Alan, I think you should read the mathmode.pdf documentation from Herbert Voss. Jan 29 '11 at 21:18

Just doing this is enough; you don't need \left and \right.

$\begin{bmatrix} z_{1}^{(1)} \\ z_{2}^{(1)} \\ \end{bmatrix} = \begin{bmatrix} a_{0}^{(0)} & a_{1}^{(0)} & a_{2}^{(0)} \\ a_{0}^{(0)} & a_{1}^{(0)} & a_{2}^{(0)} \end{bmatrix} % \begin{bmatrix} w_{10}^{(1)} & w_{20}^{(1)} \\ w_{11}^{(1)} & w_{21}^{(1)} \\ w_{12}^{(1)} & w_{22}^{(1)} \end{bmatrix}$


I was confused by the answers and the syntax so I'll share mine and include an image. I'm using which is arguably less convenient but also more verbose for beginners (like myself) than using the \[ syntax.
To be clear, what is causing the matrices to be on separate lines is the blank line between the min the code. If you fill it with the placeholder % or remove the line completely it will render like the attached picture. (Thanks to Teepeemm for clarifying what % is!)

$$\begin{bmatrix} C_1 & C_2 & C_3 & C_4 \end{bmatrix} % \begin{bmatrix} z_1 \\ z_2 \\ z_3 \\ z_4 \\ \end{bmatrix}$$


• The % in the middle is a place holder that doesn't need to be there. TeX doesn't allow have a blank line, so the % gives a line that isn't blank but doesn't have any consequences. Also, the \[ syntax is equivalent to \begin{equation*}. (without the *) will number the equation. Dec 5 '18 at 15:29
• Thanks for your clarification on the %. That explains why my matrices didn't line up side-by-side when adding a space between them. They do however line up correctly without the % and without an empty line between them. Thanks for clearing that up for me! :) I'll modify my answer. Dec 6 '18 at 17:30