# LaTeX showing old images in preview

1. ### Jonathan Scott

1,340
I've been trying to use LaTeX in a response, but the preview keeps showing images of different LaTeX expressions which I used in previous responses. This happens even for the most trivial case such as just a single letter X, both in ITEX and TEX tags. Is there something I need to do to reset it in some way?

### Staff: Mentor

$$6 \,\frac{Gm}{c^2a(1-e^2)}$$

You will get an old image if your LaTeX code is invalid. For example, with [noparse]$$\frac {GmM{r^2}$$[/noparse]

I see $r^2$. You will see

$$\frac{GmM{r^2}$$

Edit:
Hmmm.

The "LaTeX image generation failed" is being shown for a valid LaTeX expression and the generated LaTeX image for the invalid expression is the image corresponding to the valid expresion. Weird.

3. ### Redbelly98

12,017
Staff Emeritus
I will echo Jonathon's observation. It's frustrating when you're trying to give accurate information, and equations won't display properly. As a result I avoid using LaTex if at all possible. Luckily there are some symbols available for cutting-and-pasting, but they're not as versatile as LaTex.

4. ### Kurdt

4,941
Staff Emeritus
I think its a cache issue in the preview screen. This has been known about for a while. If you refresh each time you preview the problem should go away. Make sure you copy the contents of your post just in case something happens in the refresh.

5. ### Redbelly98

12,017
Staff Emeritus
I'm pretty sure I tried a screen refresh the last time this happened to me (at least 2 weeks ago), and it didn't help. But enough time has passed that I'm not 100% sure. I'll try to remember trying this next time it happens.

6. ### Ed Aboud

201
Whats the difference between TEX and ITEX anyway?

7. ### Kurdt

4,941
Staff Emeritus
itex is inline latex so if you want an equation in a sentence it will not skew the lines of text.

201
Oh right.

9. ### Redbelly98

12,017
Staff Emeritus
I just made a post with Latex and found that:
• Refreshing in preview mode does not get rid of the old LaTex image
• Refreshing after actually posting does get rid of the old image and displays the correct one.

At least this is the case in Firefox, the browser that I use.

So this puts us in the somewhat awkward position of having to post, where others can view, before we are finished editing. I guess we can always put "WORK IN PROGRESS, DO NOT RESPOND (YET)" at the top of a post until it is really in its final form.

10. ### Kurdt

4,941
Staff Emeritus
Oh well. That theory is shot down then.

11. ### Redbelly98

12,017
Staff Emeritus
Not totally shot down. At least we have some way of seeing what should be there, even if it's not perfect.

12. ### Fredrik

10,141
Staff Emeritus
I'm using Firefox too, and I don't have a problem with previews. Sometimes the wrong image shows up when I view what I just posted, but a refresh always takes care of that.

Edit: I got an old image in the preview today. I had already previewed the page and it looked fine except that I had written e(ipx) instead of e^{ipx}. So I changed it and previewed again. The old image was still there. Refresh didn't help. Then I noticed that I had actually written e^{ipx). So I replaced the ) with a } and previewed again. This time it looked the way I intended it to. No refresh needed.

Last edited: Dec 1, 2008