Just to update occurrence of problems relating to this bug. I've just looked at

I occasionally check the tracking categories. For the last few weeks they have been clear, but you do still get occasional batches of articles failing. I've recently seen 20+ articles in https://en.wikipedia.org/wiki/Category:Articles_with_math_errors most seem to actually be OK when I look at the article with maybe five requiring a null edit to fix. I did fix a batch at the end of Jan.

I've run a modified version if IKhitron's query on en-wiki The query is at https://quarry.wmflabs.org/query/14837 and the results are at https://en.wikipedia.org/wiki/Wikipedia_talk:TemplateData#Top_templates_with_no_template_data.

Following a discussion at https://en.wikipedia.org/wiki/Wikipedia_talk:WikiProject_Mathematics#.5Cbmod_does_not_work. it seems like this is an old bug with the texvc renderer. Hardy is using that setting for his preference. It works fine with the MathML/SVG renderer.

The problem seems to be the \emph{w} syntax. This syntax is not listed on the supported latex at https://en.wikipedia.org/wiki/Help:Displaying_a_formula and is not suported by MathJax.

It is a little annoying. But I'm convinced it is worth the extra effort. In time the number of false positives will go down and each page is re-rendered. Some talk pages which discuss rendering errors will remain.

The new teaching category https://en.wikipedia.org/wiki/Category:Pages_with_math_errors
makes it easy to watch for changes.

It looks like this is fixed in T134872 by https://gerrit.wikimedia.org/r/292576 We can probably close this as a duplicate.

So we now seem to have [[Category:Pages with math errors]] on en wiki at least.

A simpler test case is

There is a more specific category T49037 for a category for pages with maths error. Thats more important to me than this one.

There is a task T49037 for a tracking category for errors in math formula. With something like that it would be easier to find and fix error. I'm not sure if its technically possible for this situation when errors occur without there being an edit.

In T131177#2343273, @TTO wrote:

This change means that it is no longer possible to copy and paste math (from Chrome at least). It might help to make the SVG fallback an actual inline image, but I can't even seem to get that to copy and paste.

I know a lot of people that copy and paste equations from Wikimedia sites (WP and WB) as a quick and easy way of displaying them in presentations and the like, and this is going to break that.

In T131177#2251400, @Physikerwelt wrote:

Update with regard to 3: It took a while but we got plenty of feedback now. As a result we reconsidered to decision to delver MathML as default for firefox users. Now they get SVG's as well and need to install a add on which provides really good MathML support.

A search on google
https://www.google.co.uk/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=%22Failed+to+parse%22+site:wikipedia.org
gives about 1800 result.

They happened on
https://en.wikipedia.org/w/index.php?title=User:Salix_alba/sandbox&direction=next&oldid=723079790
it occurred for a period of about 30 min at roughly 22 hours UTC last night. The same page rendered fine later.

Just a standard webpage with normal mathjax

The way these appear in standard latex is shown below

I did a scan of my 2014 dump of the english wikipedia and found no instances of the [h] parameter, but there was one instance of \begin{array}[l] in
https://en.wikipedia.org/wiki/Spin_angular_momentum_of_light
which I've fixed.

I'm not sure about a banner but It should probably go in the Tech news https://meta.wikimedia.org/wiki/Tech/News
which appear in the Signpost and elsewhere.

I'm still getting sporadic

"Math extension cannot connect to Restbase."

and

Failed to parse (Conversion error. Server ("https://en.wikipedia.org/api/rest_") reported: "Cannot get mml. Server problem."): R_{2}

errors. I get a different set of errors each time I press "Show preview" without changing the text.

Its the option [h] parameter in

\begin{array}[h]{rcl}

remove that and things work fine

\begin{array}{rcl}

Seems like its the optional parameter

\begin{arrray}{rcl} ...

works fine but

\begin{arrray}[h]{rcl} ...

fails. I'm not sure what the parameter did and can see any difference or any documentation for the syntax.

This has also been discussed on https://en.wikipedia.org/wiki/Wikipedia:Village_pump_(technical)#MathML_glitch
it seems like some edits are corrupting the mathematics in some pages, and the pages needed to be purged. It seems to be articles which were edited at around 22:22 on 31 May 2016

Further to the above. My preference was set to "MathML with SVG or PNG fallback" before the rollout. When I started editing in the source editor the preview was full of red error messages. These persisted when saving.

It very very broken at the moment. On en.wikipedia.org

Just wondering how this works with VE. Currently when editing with VE on mediawiki.org (which I beleive has the new system). The VE displays existing equations in PNG mode, but if you edit them it seems to switch to SVG mode. After a save re-editing seems to all be in SVG mode. I'm also seeing more space than I'd like around display equations in VE

Ok. What are you expecting to happen? Just ignore the command? For me throwing an exception seems the right thing to do.

Should the title be changed as it's really more enable SVG by default. No browsers are getting MathML.

It looks like there is a typo in "executeComamnd" which I guess should be "executeCommand".

Is this fixed? It is displaying the correct formula now.

There is a discussion at https://en.wikipedia.org/wiki/Wikipedia:VPT#Math_inside_wikilinks_broken.3F related to this issue. T27417 and T103269 have been mentioned.

The issue of long lines in diff's has come up on Jimbo's talk page
https://en.wikipedia.org/w/index.php?title=User_talk:Jimbo_Wales&oldid=707364953 Section "We have to fix the software, nobody else will"

I've fixed up the goal template. Template data is not a good fit when it uses many positional parameters basically you want to do something like

Providing a link to the template documentation page would be useful for some complex templates like https://en.wikipedia.org/wiki/Template:Coord which is almost impossible to describe using TemplateData. This is bug T51772.

A lot of blocking tasks have been removed, without explanation. This leaves some questions

In T111712#1856565, @Esanders wrote:

In T111712#1855705, @Debenben wrote:

(2) it is awkward to write compared to :<math>

It is a bit longer, but :<math> is semantically just plain wrong. We need to keep the wikitext sensible, but abusing other features (definition lists) to achieve the desired styling is untenable.

My first though on trying the editor on http://en.wikipedia.beta.wmflabs.org/wiki/Equation?veaction=edit relates to T59437: "Allow the VE dialog for math elements to be movable and resizable".

I've now updated the list at https://en.wikipedia.org/wiki/Wikipedia:TemplateData/List well over 1000 templates have now had template data added. There are still plenty of high use templates yet to do.

I think we should stick to this task. Integrating citoid with the existing editors. I would start targeting the https://en.wikipedia.org/wiki/Help:Edit_toolbar which already has quite a workable citation features. Extending that to use citoid would be a quite short manageable product which real short term benefits. I know nothing about the standard wikitext editor and the edit toolbar so I'm not sure how complex that part of the task is or even which project its part of.

Adding this as a cross-wiki reference mechanism depends quite a lot on how references are done on other non-English wikis. I suspect other wikis use a similar system to the English one. Italian and Spanish have a {{cita web}} template which looks like a direct copy of the English {{cite web}}.

If we made display=block the default, we'd need to go change the (relatively few) inline examples, but it'd be a lot easier in future (in fact, there'd be one fewer characters to write for the default case).

Are we thinking of a editor for the raw LaTeX or are we looking at some sort of gui like words equation editor?

The latter.

Is this going to be a new product to the one already there? Are we thinking of a editor for the raw LaTeX or are we looking at some sort of gui like words equation editor? (Most of wiki-project maths are only interested in the former

Just to slightly update the CSS. You need
.mwe-math-fallback-image-display,
.mwe-math-mathml-display {

margin-left: 1.6em !important;
margin-top: 0.6em;
margin-bottom: 0.6em;

}
.mwe-math-mathml-display math {

display: inline;

}
To get the top and bottom margins to match the DL style. The values seem accurate to 1px.

I admit that VE is a bit off topic, but I as explained on WP:VE/F it does impact on VE. As far as I can see there is currently no way for VE to produce display maths equations which match the dominant style conventions. I can't see an option to produce the definition list <dd> tag through VE. For VE to be usable in maths articles either <dd> needs to be supported or the CSS suggestion needs to be rolled out to all wikis. A slightly more flexible option might be to have display="indent" option, but that might be overkill.

As well as a specific wiki this task addresses the default for all wiki's. These seem to be specified at https://phabricator.wikimedia.org/diffusion/EMAT/browse/master/modules/ext.math.css

Seems like it affecting new images. I I look at an existing page everything looks good. Once I start editing the page all the equations display as blank.

In reply to Fylwind I've got the same problem and created a bug T108388. Looks like things are working properly now but some pages are still failing.

Seems to have cured itself now. Is there still the action=purge&mathpurge=true option to force regeneration of images? Thats mentioned in Help:Formula but it might be out of date.

About a year back I scanned the database dump to find every instance of mathematical formula. I've got these saved as a bunch of text files so it quite easy to do a grep on them to find uses of specific commands. There are 545870 equations in total and the files are about 35MB.

Some experiment has shown its pretty easy to have client side MathJax through user javascript pages. The minimal script is

I just looked at his example page with SVG rendering and it fails there as well. Unicode characters are not really supported.

The miss match of sizes between inline math equations and surrounding text seems to be down to fonts.

I've run Help:Formula through KaTeX. There is quite a lot missing, the biggest is lack of \operatorname. This has such extensive use throughout wikipedia that it alone rules KaTeX out.

Lets look at the difference in rendering between the different modes.

I think it might correspond to the
Other,Other,Other,Other,249762000,3.3465706902
line in the Desktop Editor file. Mozilla might be a catch all for anything which has

This has now dropped to 3.71% and MSIE 11 is being recognised with 6.21%. http://stats.wikimedia.org/archive/squid_reports/2015-03/SquidReportClients.htm
You can see the change happened between 2014-08 and 2014-09 when MSIE started being picked up.