# How to type formula in tex at PF?

1. Sep 24, 2005

### Dale12

I used "search" by typing "tex" but only find a thread, it seems to said that by using $$...$$ , you can type formula well.
So I tried this and preview the post, but it was not valid, and I was confused.
I just typed like below,thx:

$$\nabla(\bf{x}\cdot \bf{a})=\bf{a}+\bf{x}(\nabla\cdot\bf{a})+i(\bf{L}\times\bf{a}) \ \ where \ \ \bf{L}={\frac{1}{i}}(\bf{x}\times\nabla)$$

Last edited: Sep 24, 2005
2. Sep 24, 2005

### Moonbear

Staff Emeritus
Here's a thread where you can view other people's code and try your own (you're allowed to just practice using LaTex in it). It's a sticky thread in the General Physics forum in case you don't bookmark it and need to find it again later.

3. Sep 24, 2005

### Dale12

thanks, I just found it^_^. and before this, I found formula I type can be shown normally, it's glad to see this. but still there are two question:
1. it says that we use tex & /tex, but how to add [] in the beginning and the end to tell others or just show this as explanation , because they disapper as tags after u post them.
2. how to begin a second paragraph or how to type enter in formula here? I tried to insert "\\" before "where" above but failed.

Last edited: Sep 24, 2005
4. Sep 24, 2005

### Dale12

IC, thanks anyway!
1.Just add several spaces as [ tex ]...[ /tex ] .
2.add two [ tex ]...[ /tex ] can print as an "enter",maybe like below:

$$\nabla(\bf{x}\cdot\bf{a})=\bf{a}+\bf{x}(\nabla\cdot\bf{a})+i(\bf{L}\times\bf{a})$$
where
$$\bf{L}={\frac{1}{i}}(\bf{x}\times\nabla)$$

Last edited: Sep 24, 2005
5. Sep 24, 2005

### Tom Mattson

Staff Emeritus
There's also another set of tags: [ itex ](stuff)[ /itex ]. The "i" stands for "inline", and it does just that: It lines the TeX up with the rest of your text. Check it out.

With [ tex ] tags:

The Lorentz factor in natural units is $$\gamma=\frac{1}{\sqrt{1-v^2}}$$.

And with [ itex ] tags:

The Lorentz factor in natural units is $\gamma=\frac{1}{\sqrt{1-v^2}}$.

6. Sep 25, 2005

7. Oct 8, 2005

8. Oct 8, 2005

9. Oct 8, 2005

### Tom Mattson

Staff Emeritus
Yeah, then it can get ignored right along with the other sticky that's there (the one that says, "Read this before posting.")

Eh, maybe I'll make my own sticky that has the most commonly used equations in basic physics.

10. Oct 9, 2005