Bad kerning of decimal separator in MathML
Closed, ResolvedPublicBUG REPORT
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	Dexxor
	Aug 11 2025, 6:51 PM

Description

Enable "Client side MathJax rendering" in Special:Preferences → Apperance → Math. Then preview a page with the contents <math>0.99</math>. There is too much space around the decimal separator.

This is because in the generated MathML every digit is put inside its own <mn> element and the decimal separator is put inside <mo>:

<mn>0</mn>
<mo stretchy="false">.</mo>
<mn>9</mn>
<mn>9</mn>

This is bad as the number 0.99 is a single semantic token. https://temml.org/ generates <mn>0.99</mn> instead.

Also see T390260

Details

Related Changes in Gerrit:

	Subject	Repo	Branch	Lines +/-
	Handle comma as decimal separator	mediawiki/extensions/Math	master	+30 -3
	Squash numbers in TexArray	mediawiki/extensions/Math	master	+65 -35

Customize query in gerrit

Related Objects
Search...

Status	Subtype	Assigned	Task
Open	Feature	JeanCASPAR	T397585 Provide a macro for putting arbitrary Unicode content in <mo> tag
Open		Physikerwelt	T271001 Transition to MathML rendering as default
Open		None	T375318 Native MathML mode formatting bugs
In Progress	BUG REPORT	Physikerwelt	T375238 Client-side MathJax rendering problems
Resolved	BUG REPORT	Physikerwelt	T401623 Bad kerning of decimal separator in MathML
Resolved		Physikerwelt	T405439 Investigate <math>1\definecolor{c}{RGB}{255,0,0}+2</math>

Event Timeline

Dexxor created this task.Aug 11 2025, 6:51 PM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptAug 11 2025, 6:51 PM

Dexxor added parent tasks: T375318: Native MathML mode formatting bugs, T375238: Client-side MathJax rendering problems.Aug 11 2025, 6:52 PM

SalixAlba subscribed.Aug 11 2025, 9:42 PM

Christian1985 subscribed.Aug 16 2025, 11:29 AM

Physikerwelt claimed this task.Sep 18 2025, 5:52 PM

Change #1189628 had a related patch set uploaded (by Physikerwelt; author: Physikerwelt):

[mediawiki/extensions/Math@master] WIP: MathJax spacing of numbers

https://gerrit.wikimedia.org/r/1189628

gerritbot added a project: Patch-For-Review.Sep 19 2025, 6:00 AM

Physikerwelt moved this task from Inbox to Code Review on the Math board.Sep 19 2025, 10:39 AM

With the patch above <math>0.99</math> also generates <mn>0.99</mn>. The regexp for merging is /[0-9.]/. Please let me know if that should be extended to other decimal-separators.

Physikerwelt triaged this task as Medium priority.Sep 19 2025, 9:44 PM

On dewiki, it's common to use {,} as decimal seperator, e.g. 3{,}14. Support for that would be nice as well.

Ok, it works in TeX. However, it does not seem to make a difference for either mathoid, Temml, or LaTeXML if curly braces are used or not.

Change #1189970 had a related patch set uploaded (by Physikerwelt; author: Physikerwelt):

[mediawiki/extensions/Math@master] Handle comma as decimal separator

https://gerrit.wikimedia.org/r/1189970

In T401623#11199076, @Dexxor wrote:

On dewiki, it's common to use {,} as decimal seperator, e.g. 3{,}14. Support for that would be nice as well.

This works now as well. However, I excluded {,}99' and 0,99`. As I was unsure if {,} might have a different meaning in some situations, for example, within mhchem.

Is that OK?

I don't fully understand what you excluded, but dewiki never uses numbers without a leading digit so while .99 (point nine nine) should be squashed, it's OK if {,}99 isn't.