Math & Science ⇒ Height of the lines in equation systems

[Acide Amine]

Hello,

I am writing equation systems with a left brace, like this for instance :

Code: Select all

\begin{equation}
  \left\{
    \begin{array}{c}
      \frac{\partial{u}}{\partial{x}} + \frac{\partial{u}}{\partial{x}} = 0 \\
      \frac{\partial{p}}{\partial{x}}  = 0 \\
    \end{array}
  \right.
\end{equation}

My problem is that when doing this, each line appear smaller than if it wasn't in the array environment. This is annoying when writing bigger equation systems, with a lot of fractions. It becomes too small.

What I would like to do is to be able to write equation systems with a normal size for the equation, as if I did this :

Code: Select all

\begin{equation}
      \frac{\partial{u}}{\partial{x}} + \frac{\partial{u}}{\partial{x}} = 0 \\
\end{equation}
\begin{equation}
      \frac{\partial{p}}{\partial{x}}  = 0 \\
\end{equation}

(But then there is no left brace.)

Can somebody help ?

Thanks,
Amine

[alainremillard]

Two things to help you

First, you can expand any part of an equation using \displaystyle. For a fraction, they provided the dfrac{}{} command that always put the fraction in displaystyle, instead of scriptsize.

Second, to simplify your code, there is an {cases} environment that does exactly what you want. It as to be in math mode, but it but the brace before.

Code: Select all

\begin{equation}
    \begin{cases}
      \dfrac{\partial{u}}{\partial{x}} + \dfrac{\partial{u}}{\partial{x}} = 0 \\
      \dfrac{\partial{p}}{\partial{x}}  = 0 \\
    \end{cases}
\end{equation}

[Acide Amine]

Hi Alain,

Thanks a lot for the dfrac{}{} command that did exactly what I wanted.

The cases{} environment would have been perfect if it allowed to center each line. By default, it writes each cell of the table with a left alignement : as I want to be able to chose the alignement, the array{} suits my needs better (unless I missed the alignement feature of cases{})

Amine