# How to make equations the same size

When I write an equation using the simple $ and $, it comes out to the correct size, with the fractions bulging above and below the lines and the parentheses surrounding them.

But when I use the {array} environment, the equations become squished, and all the fractions are squeezed into the line.

How can I get the array environment to look the same as if I were typing an individual equation?

$I(a;b)=I\left(\frac{1}{a};\frac{1}{b}\right)$


is what I want the following array to look like:

$\begin{array}{rcl} I\left(a;\frac{1}{a}\right) & = & I\left(\frac{1}{a};a\right) \\ I\left(a;\frac{1}{a}\right) & = & -I\left(a;\frac{1}{a}\right) \\ \hbar I\left(a;\frac{1}{a}\right) & = & 0 \end{array}$

• you could use \displaystyle but this is missusing array which is intended for arrays/matrices of numbers/data not for aligned equations. Use amsmath package align and the alignment will be displaystyle by default Jul 17, 2014 at 9:27

This is what you may need actually.

\documentclass{article}
\usepackage{mathtools}
\begin{document}
\begin{align*}
I\left(a;\frac{1}{a}\right) &=  I\left(\frac{1}{a};a\right) \\
I\left(a;\frac{1}{a}\right) &=  -I\left(a;\frac{1}{a}\right) \\
\hbar I\left(a;\frac{1}{a}\right) &= 0
\end{align*}
\end{document}


• It might look better if you used \tfrac{1}{a} ;-) Jul 17, 2014 at 9:41
• @daleif You are right probably :-)
– user11232
Jul 17, 2014 at 9:42