How do I correctly write 3x3 matrices using the text editor?

[applechu]

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.

 

[Borek]

For entering matrices see information about LaTeX: https://www.physicsforums.com/showthread.php?t=546968

 

[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

 

[spamiam]

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).

 

[applechu]

thanks