# Centering text in a tabular environment

Good day to all,

This look not beautiful for me, I want the text is centred in the box, especially $\frac{1}{s^n}$. Your help is much appreciated.

\documentclass{report}

\usepackage{amsmath}

\begin{document}
\begin{table}[H]\centering\label{laplaceintegral}
\begin{tabular}{|c|c|c|}
\hline
Item & $\text{Functions ($t$domain)}$ & $\text{Laplace Transforms ($s$domain)}$\\
\hline\hline
1&$\int_0^t x(\tau)d\tau$ & $\displaystyle\frac{1}{s}\cdot X(s)$\\ \hline
2&$\underbrace{\int_0^{t}\ldots\int_0^{t_3}\int_0^{t_2}}_{n\text{times}} % x\left(\tau_1\right)d\tau_1dt d\tau_2\ldots d\tau_n$ %
& $\displaystyle \frac{1}{s^n}\cdot X(s)$ \\ \hline
\end{tabular}
\caption{Laplace transform of integral}
\end{table}

\end{document}


-

I would suggest removing the horizontal rules separating the row entries, as well as all the vertical rules - the tabular alignment already encourages a columnar context naturally. Read more about this in the booktabs documentation.

Following booktabs' suggestion, the spaces things out a little:

\documentclass{report}
\usepackage{float}% http://ctan.org/pkg/float
\usepackage{amsmath}% http://ctan.org/pkg/amsmath
\usepackage{booktabs}% http://ctan.org/pkg/booktabs
\newcommand{\dt}{\mathrm{d}t}
\begin{document}

\begin{table}%[H]
\centering
\begin{tabular}{ccc}
\toprule
Item & $\text{Functions ($t$~domain)}$ & $\text{Laplace Transforms ($s$~domain)}$ \\
\midrule
1 & $\int_0^t x(\tau)d\tau$ & $\displaystyle\frac{1}{s}\cdot X(s)$ \\
2 & $\underbrace{\int_0^{t}\ldots\int_0^{t_3}\int_0^{t_2}}_{n~\text{times}} x\left(\tau_1\right)d\tau_1\dt d\tau_2\ldots d\tau_n \vphantom{\overbrace{\int_0^{t}\ldots\int_0^{t_3}\int_0^{t_2}}^{n~\text{times}}}$ &
$\displaystyle \frac{1}{s^n}\cdot X(s)$ \\
\bottomrule
\end{tabular}
\caption{Laplace transform of integral}
\end{table}

\end{document}


I've added a \vphantom in cell (2,2) that adds some vertical space equivalent to the drop initiated by "n times". Using \\[<len>] (where <len> is some length) would also have worked.

Finally, you need to place the \label after \caption, always. See Why does an environment's label have to appear after the caption?

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Thank you Werner, as I looked back to my university thesis guidelines, the table must have 'boxes'. But this is really look nice. Thank you so much again. –  azlanaznam Jul 21 '12 at 6:18
@azlanaznam: See if some of the suggestions in Column padding in tables helps. It's a general answer to adding space horizontally/vertically in tables. Gives some feedback once you've experimented and I could update my answer here. –  Werner Jul 21 '12 at 13:11