# Parenthesis in Matrices

• Feb 15th 2010, 08:12 AM
Swlabr
Parenthesis in Matrices
How do you put a dot-dot-dot in matrices? My current attempt of

\left(
\begin{array}{ccc}
\delta & 0 & 0 & \ldots & 0 \\
0 & \delta & 0 & \ldots & 0 \\
0 & \ldots & 0 & \delta \end{array}
\right)

doesn't work...

Also, how would I make it go down the way too...?

(I meant to say "ellipsis" not "parenthesis" in the title...)
• Feb 15th 2010, 08:53 AM
masters
Quote:

Originally Posted by Swlabr
How do you put parenthesis in matrices? My current attempt of

\left(
\begin{array}{ccc}
\delta & 0 & 0 & \ldots & 0 \\
0 & \delta & 0 & \ldots & 0 \\
0 & \ldots & 0 & \delta \end{array}
\right)

doesn't work...

Hi Swlabr,

I'm not sure of the contents of your matrix, but you didn't have enough columns indicated in your {ccccc} to match the elements in your matrix. And your third row only has 3 columns. Here's an example. See if you can work from this.

\left(
\begin{array}{ccccc}
\delta & 0 & 0 & \ldots & 0 \\
0 & \delta & 0 & \ldots & 0 \\
0 & \ldots & 0 & \delta & 0 \\
\end{array}
\right)

Hi Swlabr,

I'm not sure of the contents of your matrix, but you didn't have enough columns indicated in your {ccccc} to match the elements in your matrix. Your first row and second row have 5 columns each. Your third row only has 4. Here's an example. See if you can work from this.

$\displaystyle \left( \begin{array}{ccccc} \delta & 0 & 0 & \ldots & 0 \\ 0 & \delta & 0 & \ldots & 0 \\ 0 & \ldots & 0 & \delta & 0 \\ \end{array} \right)$
• Feb 15th 2010, 09:00 AM
Swlabr
Quote:

Originally Posted by masters
Hi Swlabr,

I'm not sure of the contents of your matrix, but you didn't have enough columns indicated in your {ccccc} to match the elements in your matrix. And your third row only has 3 columns. Here's an example. See if you can work from this.

Ohh - that'll teach me just to copy and paste commands. Thanks!

I suppose my next question is, how do I make

$\displaystyle \left( \begin{array}{ccccc} \delta & 0 & 0 & \cdots & 0 \\ 0 & \delta & 0 & \cdots & 0 \\ \vdots & \vdots & \vdots & \vdots & \vdots \\ 0 & \cdots & 0 & 0 & \delta \end{array} \right)$

look nice? I would be much nicer to have some diagonal dots...
• Feb 15th 2010, 09:30 AM
masters
Quote:

Originally Posted by Swlabr
Ohh - that'll teach me just to copy and paste commands. Thanks!

I suppose my next question is, how do I make

$\displaystyle \left( \begin{array}{ccccc} \delta & 0 & 0 & \cdots & 0 \\ 0 & \delta & 0 & \cdots & 0 \\ \vdots & \vdots & \vdots & \vdots & \vdots \\ 0 & \cdots & 0 & 0 & \delta \end{array} \right)$

look nice? I would be much nicer to have some diagonal dots...

Take a look at this site. It should answer your questions. Use \ddots for diagonal dots.