Math & Science ⇒ How to add matrix in a formula

[lynnlee]

Dear all,

I tried to add the matrix in a math formula, but the matrix was distorted in shape. The code I use is the following:

Code: Select all

\documentclass[a4paper,11pt]{article}
\begin{document}
$y=\sum_{i} x_{i} \begin{bmatrix} 1 & 1 &1 \\ 1& 1 & 1\\1 & 1& 1 \end{bmatrix}$
\end{document}

Any suggestions about how to let the matrix align in a good shape and be added to the math formula?
Thank you.

Lynn

[Johannes_B]

Hi, the code as is does not compile because amsmath is missing. Adding package mathtools (as it patches amsmath at some occasions) gives me the following.

lynnleeMatrix.png (851 Bytes) Viewed 2916 times

I can't see any distortion. Can you clarify what you mean?

[lynnlee]

Thank you so much. With \usepackage{mathtools}, the code works perfectly fine.

Lynn