Kindly increase the gap size in an array (between the \overline and the top line)

Question

Is there a simple way to increase the gap size between the \overline and the top line, in the array? More precisely, here is an example.

An array command

$$
\begin{array}{| c | c |}
\cline{1-2}
\overline{a} & \overline{b}    \\
\hline
\end{array}.
$$

outputs this.

How do we make the gap size between the top line and the \overline{b} become even just slightly larger?

Answer 1

You can use (locally) \extrarowheight.

\documentclass{article}
\usepackage{amsmath}
\usepackage{array}

\begin{document}

\[
\setlength{\extrarowheight}{2pt}
\begin{array}{| c | c |}
\hline
\bar{a} & \bar{b} \\
\hline
\end{array}
\]

\end{document}

1. Don't use $$ in LaTeX, see Why is \[ … \] preferable to $$?.

2. \cline is for rules that aren't supposed to cover an entire row.

3. \overline should be \bar, when a single character is to be overlined.