Here is something I discovered.

If you want to define a piecewise function say the absolute value function what you do is:

Code:

|x|=
\left\{
\begin{array}{c}
x \mbox{ if } x\geq 0\\
-x \mbox{ if } x<0
\end{array}
\right

If that is your whole code, then you can igonore the last part.

Code:

|x|=
\left\{
\begin{array}{c}
x \mbox{ if } x\geq 0\\
-x \mbox{ if } x<0

The reason is because there is nothing following this. You cannot do this if there would be something following the code, but other here this trick works and saves me time.

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