Math & Science ⇒ Error: ! Missing $ inserted

[luso]

Hi all,

This is the first time I need to post and that's cool. It means I've found the 100E16 answers needed before... and thanks to you xD.

But now I found four of this => Error: ! Missing $ inserted at lines 3 and 4 on the code, what is wrong?

Code: Select all

\begin{equation}
  \left( 
  \begin{array}{cc}
    $R_{3 \times 3}$ & $p_{3 \times 1}$ \\
    $0$ & $1$
  \end{array} 
  \right)
\end{equation}

Sorry if is a trivial question, but I tried all the ways to avoid it with no results.

Thanks for everything.

[Stefan Kottwitz]

Hi luso,

welcome to the board!
The complete array environment is set in math mode, you don't need those $ inside:

Code: Select all

\begin{equation}
\left(
\begin{array}{cc}
R_{3 \times 3} & p_{3 \times 1} \\
0 & 1
\end{array}
\right)
\end{equation}

You could use amsmath and a matrix environment instead:

Code: Select all

\documentclass[a4paper,10pt]{article}
\usepackage{amsmath}
\begin{document}
\begin{equation}
  \begin{pmatrix}
    R_{3 \times 3} & p_{3 \times 1} \\
    0 & 1
  \end{pmatrix}
\end{equation}
\end{document}

Stefan

[luso]

As I guess, there was a simple thing... thanks for helping.

Luso