If you don't want to use the the p{<width>}
column type where you have to fix the width to a specific amount you could typeset one row using the SetToWidest
macro as defined below. This requires that you determine what the widest entry is and define that as the value of WidestEntry
:

\documentclass{article}
\usepackage{calc}
\newcommand{\WidestEntry}{$lon_1$}%
\newcommand{\SetToWidest}[1]{\makebox[\widthof{\WidestEntry}]{#1}}%
\begin{document}
\begin{tabular}{|c|c|}
\hline
\textbf{x} & \textbf{y} \\
\hline
\hline
\SetToWidest{$t_1$} & $lon_1$ \\
\hline
\end{tabular}
or similarly using array
:
\documentclass{article}
\usepackage{calc}
\newcommand{\WidestEntry}{$lon_1$}%
\newcommand{\SetToWidest}[1]{\makebox[\widthof{\WidestEntry}]{$#1$}}%
\begin{document}$
\begin{array}{|c|c|}
\hline
\textbf{x} & \textbf{y} \\
\hline
\hline
\SetToWidest{t_1} & lon_1 \\
\hline
\end{array}$
\end{document}
If you are ok with specifying the width of each column you can use the p{<width>}
column type:
\documentclass{article}
\usepackage{array}
\begin{document}$
\begin{array}{|>{\centering\arraybackslash$} p{1.0cm} <{$} | >{\centering\arraybackslash$} p{1.0cm} <{$} |}
\hline
\textbf{x} & \textbf{y} \\
\hline
\hline
t_1 & lon_1 \\
\hline
\end{array}$
\end{document}
p{1.0cm}
as in\begin{tabular}{|p{1.0cm}|p{1.0cm}|}
, which necessitates the content being in math mode:$t_1$
. – Peter Grill May 8 '12 at 18:12l
, toc
tor
alignment, but only mentioned it as an option. – Peter Grill May 8 '12 at 18:21