# Some Latex math equations not rendering immediately after edit

I noticed that in some cases, some Latex math equations are not rendering immediately after an edit (I need to refresh the page so that they get rendered).

Here is an example I can reproduce on this question:

I use Google Chrome if that matters.

## 1 Answer

This is probably due to the \label{mu} in the expression in question. Note that the expression is rendered, but it contains an error, which is what the black outline indicates. In this case, what I suspect is happening is that when you edit the problem, the equation is rendered and its label is defined. Then when the problem is saved, the equation is rendered again and the label is now already defined, so the second rendering causes an error about labels being used multiple times. (Note that during the editing process, the preview editor is set up to prevent the duplicate label error, but if the problem is re-rendered on the same page after editing, as it appears to be here, that is not the case.)

In any case, you can probably eliminate the issue by removing the \label, since it is never used anyway. (But that would not help in a situation where you really did need the label.)