# Math Help - Testing LaTeX 2

1. ## Testing LaTeX 2

$f(x)={{3x\quad\text{if}~~x>0}\brace{5x\quad\text{i f}~~x\leq{0}}}$

Does anyone think that is an easier way to do piecwise functions?

2. That's a nice way. But for piecewise, the norm is usually one left bracket. I mostly do it like so. But I like your way.

$f(z) = \left\{ \begin{array}{rcl}
3x & \mbox{if} & x<3 \\ 5x & \mbox{if} & x\geq {3}
\end{array}\right.$

3. Originally Posted by galactus
That's a nice way. But for piecewise, the norm is usually one left bracket. I mostly do it like so. But I like your way.

$f(z) = \left\{ \begin{array}{rcl}
3x & \mbox{if} & x<3 \\ 5x & \mbox{if} & x\geq {3}
\end{array}\right.$
Thanks Galactus. Does anyone know how to add three elements with this \brace command?

${x}\brace{{y}\brace{z}}$

Like that but obviously I want the z and y to be the same size as the x, and no brace.

4. $|x| =
\begin{cases}
x, & \mbox{if}~x \ge 0 \\
-x, & \mbox{otherwise}
\end{cases}
$

Code:
|x| =
\begin{cases}
x, & \mbox{if}~x \ge 0 \\
-x, & \mbox{otherwise}
\end{cases}
Neat .

5. Originally Posted by cyph1e
$|x| =
\begin{cases}
x, & \mbox{if}~x \ge 0 \\
-x, & \mbox{otherwise}
\end{cases}
$

Code:
|x| =
\begin{cases}
x, & \mbox{if}~x \ge 0 \\
-x, & \mbox{otherwise}
\end{cases}
Neat .
I do not suppose that was supposed to be an answer to my question?

Neat indeed, but I hate having to write all that \mbox stuff

6. Originally Posted by Mathstud28
${x}\brace{{y}\brace{z}}$

Like that but obviously I want the z and y to be the same size as the x, and no brace.
Like this?

$\left\{\begin{array}{c}x\\y\\z\end{array}\right\}$

7. Originally Posted by Catherine Morland
Like this?

$\left\{\begin{array}{c}x\\y\\z\end{array}\right\}$
Yes, thank you very much. I know that way, I was just hoping there was an easier way involving the \brace command, thanks again.

8. Originally Posted by Mathstud28
I do not suppose that was supposed to be an answer to my question?

Neat indeed, but I hate having to write all that \mbox stuff

I was just demonstrating that when using cases you don't need \left{.

9. $\left. \begin{array}{c|c|c|c|c|c} 1 & \tfrac 12 &+& \tfrac 13 &+& \tfrac 16 \\ \hline
3 & \int_0^2 x^2 \, dx &+& \int_0^1 x^3 \; dx &+& \tfrac 13 \int_0^1 x^3 ~dx \end{array} \right\} \Leftrightarrow \rm{teable.}$

Ou..nice one

10. Few commands that I've just discovered (see [1]) and which can be useful :

To write text under/over an arrow one can use \xrightarrow[subscript]{superscript} and \xleftarrow[subscript]{superscript}. If the subscript/superscript is too wide the arrow is automatically extended.

$f(x)\xrightarrow[x\to 0]{}42 \text{ and } f(x)\xrightarrow[\text{sometimes}]{} 1
$

The command \cfrac{}{} gives continued fractions (to get the same result using \frac{}{} one has to use \displaystyle) :

$\cfrac{1}{1+\cfrac{1}{1+\cfrac{1}{1+\cdots}}}$

To get multiline subscripts and superscripts : \substack{ first line\\ second line\\ third line \\ ... }

$
\theta(n) = \sum_{\substack{
1\leq i\leq n\\
1\leq j\leq i}} i\times j
\text{ and } f(x,y) \xrightarrow[\substack{x\to 0\\y\to 0}]{} 42$

For those of you who integrate functions of more than four variables :

$\idotsint\limits_{ \mathbb{R}^n}\varphi(x_1,x_2,\ldots,x_n)\,\mathrm{ d}x_1\mathrm{d}x_2\ldots \mathrm{d}x_n$

Edit : To get a small matrix one can use... \begin{smallmatrix}...\end{smallmatrix}. It gives something like this : $\begin{smallmatrix} 1 & 2 \\ 3 & 4 \end{smallmatrix}$.

[1] http://pages.usherbrooke.ca/cimel/im...math_guide.pdf (not all the commands given in this file are available on the forum...)

11. Just testing for he first time myself, sorry.

$\frac{10-(-9.9)}{2}, " alt="\frac{10-(-9.9)}{2}, " />

$\frac{2\pi}{b} =12.5$

12. $\Sigma^{n=2}_{k=3}{b}=12.5$

13. $
\mbox MnO_2
$

14. ## ?

[tex]z=(4+\sqrt15)^1/3 +(4-\sqrt15)^1/3[tex]

15. ## testeing

z=(4+\sqrt15)^1/3

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