Math & Science ⇒ Having trouble getting this equation set up correctly

[MathPaula]

I've added and deleted dollar signs until my eyes are blurry. Can anyone see what's wrong with this set up?

Code: Select all

$d_{H}(X,Y)=\left\{$ \begin{array}{ll} $ \left|x_{1}-y_{1}\right|$,
 & $\mbox{if $x_{2}=y_{2}$} $\\ $\left|x_{1}\right|+\left|x_{2}-y_{2}\right|
 +\left|y_{1}\right|$,
 & $\mbox{if $x_{2} \neq y_{2}$}$ \\ $\left|x_{2}-y_{2}\right|$,
 & $\mbox{if $x_{2}=y_{2}=0$}$ \end{array} $\right\}$.

It's supposed to be a piecewise function with three parts. I'm pretty sure I have too many $ in there, but TXC keeps giving me a missing $ error and I can't figure out where it is and am afraid I've added too many now, because I'm now getting a fatal error upon building. It was working and formatting and building just fine an hour ago.

Thanks in advance,

PGY

[Stefan Kottwitz]

Hi PGY,

welcome to the board!

Here are some tips:

• the array environment works in math mode, no additional $ required
• End \mbox when the text ends, don't nest math and \mbox if it's not necessary.
• Even better, use \text instead of \mbox, loading the amsmath package is required.
• Use line breaks and indentation in the editor to make your code more readable.
• If there's only one character or number in a subscript or superscript, you don't need braces. Omitting them can make the code easier to read, though in general I don't recommend to omit braces whenever possible - they can help.

Code: Select all

$d_{H}(X,Y)=\left\{
  \begin{array}{ll}
    \left|x_1-y_1\right|, & \text{if } x_2=y_2 \\
    \left|x_1\right| + \left|x_2-y_2\right| + \left|y_1\right|,
      & \text{if } x_2 \neq y_2 \\
    \left|x_2-y_2\right|, & \text{if } x_2=y_2=0
  \end{array} \right\}.$

equation

equation.png (3.77 KiB) Viewed 1606 times

Btw. our forum supports code markup. You can use the Code button above the edit field when writing or editing. I just did this for you.

Stefan

[MathPaula]

Thanks a million!