# Different behavior in parsing LaTeX code in the previewer and in the saved post

I posted this answer a few minutes ago. After the display, I had written $\int_E f\\,d\mu$ to get the thin space; the previewer parsed it correctly (and parsed it incorrectly without the double backslash, displaying the comma instead). After I saved, if I had \\, then the post complained of a misplaced \\ and did not display the formula; if I had the single backslash, \,, then it displayed correctly.

In other words, the previewer was doing one thing, while the final display was doing another.

• It just happened again with math.stackexchange.com/questions/9825/…, this time with \\{ which displayed correctly in the previewer, but led to complaints after it was saved; removing the double backslash led to incorrect display in the previewer, correct when saved. – Arturo Magidin Nov 11 '10 at 6:18
• I suspect, though I have no official information, that you may be experiencing the results of some attempts at "fixing" the need for the doubled-backslashes inside $. – Isaac Nov 11 '10 at 6:56 • My problem in math.stackexchange.com/questions/9833/… might be related to this error. – AD. Nov 11 '10 at 8:10 • I've run into other problems with displayed equations using $$. I have no objection to settling on either behaviour, but the fact that the preview and the server are behaving differently is a definite problem. – Arturo Magidin Nov 11 '10 at 15:53 ## 1 Answer This is new behavior. All content between $$ on sites with LaTeX rendering enabled will not be converted from markdown. This means it is no longer necessary to escape \ or other special markdown sequences. This only applies to newly created (or edited) posts, old posts will continue to render correctly. Currently the post preview pane still shows the old behavior (similar to the new syntax). A fix for this is planned. The preview should correctly ignore content between $\$ now.

• If a fix is planned, then is it really status-bydesign? – Isaac Nov 11 '10 at 18:58
• @Isaac - yes, if only for a lack of [status-expect-additional-improvement-in-the-future]. – Kevin Montrose Nov 11 '10 at 19:05
• Isn't that what [status-deferred] is for? – Isaac Nov 11 '10 at 19:05
• Well, I hope the previewer gets updated soon; I'm going to be doing a lot of edits until then... – Arturo Magidin Nov 11 '10 at 20:00
• Great! Thanks for the work. Can this be extended to environments (\begin{stuff}...\end{stuff}) as well? – kennytm Nov 11 '10 at 20:42