# proper display but error shows during compile

I havewritten the following code, the display is correct but the texmaker shows errors such us "missing $inserted" and "display math should end with$\$".

\documentclass[10pt,a4paper]{book}

\usepackage[utf8x]{inputenc}
\usepackage[greek]{babel}
\usepackage{amssymb,amsmath,latexsym,amsfonts,amsthm,cleveref}
\begin{document}

$$\Bbb H =\Bigg{ \lbrace \begin{pmatrix} 1 & x_1 & x_3 \\ 0 & 1 & x_2 \\ 0 &0 & 1 \end{pmatrix} \in GL(3,\mathbb{R})} : x_1,x_2,x_3 \in \mathbb{R} \Bigg \rbrace$$

\end{document}

In this case, I'd use \left\{ \right\} to adjust the braces. But you can also use another fixed sizes, e.g. \Biggl\{ \Biggr\} (not so tall)

\documentclass[10pt,a4paper]{book}

\usepackage[utf8x]{inputenc}
\usepackage[greek]{babel}
\usepackage{amssymb,amsmath,latexsym,amsfonts,amsthm,cleveref}
\begin{document}

$$\mathbb{H} = \left\{ \begin{pmatrix} 1 & x_1 & x_3 \\ 0 & 1 & x_2 \\ 0 & 0 & 1 \end{pmatrix} \in GL(3,\mathbb{R}) : x_1,x_2,x_3 \in \mathbb{R} \right\}$$

\end{document}

• Adding that the main error was the blank line inside the equation environment. – egreg Sep 17 '15 at 14:24