Hi:
I am a newbie to this forum, and I don't know how to
use the text editor correctly. If I hope to write an 3x3 matrices,
how to key in it correctly in this thread.
and furthermore, if there any manual about the editor, thanks a lot.

 PhysOrg.com science news on PhysOrg.com >> 'Whodunnit' of Irish potato famine solved>> The mammoth's lament: Study shows how cosmic impact sparked devastating climate change>> Curiosity Mars rover drills second rock target
 I have tried a example as following, but still not work: \begin{matrix} 1 & 1 & -1\\ 1 & -1 & 1\\ 1 & 1 & 1 \end{matrix} is there any other method, thanks

 Quote by applechu I have tried a example as following, but still not work: \begin{matrix} 1 & 1 & -1\\ 1 & -1 & 1\\ 1 & 1 & 1 \end{matrix} is there any other method, thanks
That looks pretty good! If you want round parentheses around your matrix use pmatrix:
$$\begin{pmatrix} 1 & 1 & -1\\ 1 & -1 & 1\\ 1 & 1 & 1 \end{pmatrix}$$
and for square brackets use bmatrix:
$$\begin{bmatrix} 1 & 1 & -1\\ 1 & -1 & 1\\ 1 & 1 & 1 \end{bmatrix}$$.

Also, surround your LaTeX with either ## or  (click 'Quote' to check out my example).

 thanks

 Tags latex matrix