Combinations in TeX

Quote:

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Originally Posted by ThePerfectHacker

Here is something I discovered.

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

Code:

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

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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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I think I would like the "if"s verticaly alligned as in:



which requires only a minor mod:

Code:

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

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RonL