# Problems with previewing posts that use LaTeX

1. Aug 20, 2004

### NoPhysicsGenius

Say that I have the following LaTeX equation:

$$x = x_0 + v_{0x}t$$

Let us then say that I click the "Preview Post" button in the "Post New Thread" dialog box.

So far, everything has gone fine.

However, say that I go to the above LaTeX equation and write (without the spaces before and after "tex" and "/tex":

[ tex ]x = x_0 + v_{0x}t + \frac{1}{2}a_{x}t^2[ /tex ]​

Then, say I click the "Preview Post" button for a second time. Guess what? The original equation still appears! Please try this to confirm what I am saying.

For more complex and multiple uses of the "[ tex ]" and "[ /tex ]" modifiers, multiple uses of the "Preview Post" button between edits leads to a mess so jumbled, I can no longer be confident that my message will be submitted intact. I find LaTeX to be a bit intimidating in the first place. As such, because of the problems I have been having with the "Preview Post" function, I have yet to use LaTeX in any of my posts. However, I need help with a problem using vectors, and I believe that the only way I will be able to generate an understandable post will be via the use of LaTeX.

So what is going wrong?

If this is an issue with my browser, I'll point out that I'm using Microsoft Internet Explorer 6.0 under Windows XP Service Pack 1.

If this isn't an issue with my browser, do you plan on fixing this problem any time soon?

Thank you.

P.S. I am assuming that when I finally get around to clicking on the "Submit New Thread" button that everything will be displayed correctly ...

Last edited: Aug 20, 2004
2. Aug 21, 2004

### chroot

Staff Emeritus
It is, in fact, a browser issue. Your browser is caching the images, even when it should not. Some users have this problem, while most do not. I will look into modifying the .htaccess to force Pragma: no-cache ASAP to see if it makes any difference for you. The majority of our users have no problem.

The final images generated after clicking Submit are different than those generated by the preview and will not be affected.

- Warren

3. Aug 21, 2004

### employee #416

Errr...I have this same problem.

4. Aug 22, 2004

### zefram_c

I've noticed this too. Pressing the Refresh button usually helps. Also make sure your tex is properly formatted, all tags are closed, etc, etc. I once put in a malformed tex string that the processor obviously couldn't do anything with, and IE displayed a tex image from a different post of mine.

5. Aug 22, 2004

### chroot

Staff Emeritus
Okay, I've added expiration directives to the latex_images directory. Please let me know if the problem goes away.

- Warren

6. Aug 24, 2004

### NoPhysicsGenius

Great news ... The "Preview Post" function now works for me with LaTeX. Thanks!

7. Aug 24, 2004

### plover

Thanks! I've also had all the problems mentioned above at times. It has never been consistent though.

(And FWIW, it is not an IE thing as I'm using Firefox.)