For MathML syntax, tutorial and editor all in one-stop shopping go here:
Good nitpick, but I think MathJax is the name of the library Discourse uses, while MathML is the name of the markup language that MathJax implements.
Although I suspect you are for more expert in these matters than I. I know I don’t know in what ways MathJax may be a subset or superset or incompatible with MathML.
MathML is an XML-based markup language. You probably aren’t writing it by hand or even by tool. Instead, you’re writing \LaTeX , or at least a \LaTeX -inspired syntax that implements some subset of it.
I don’t think there’s a way to pass MathML syntax directly to MathJax via Discourse, though MathJax is capable of rendering it. I suspect that MathJax first converts LaTeX to MathML internally and then the rendering engine works on MathML.
Actually, it’s doing something much more manual than that. MathML isn’t implemented fully or well on most browsers (Firefox I think has the most complete implementation). MathJax pretty much rolls its own by default. If you right-click on a sample of math (as in my post above), under “Math Settings” you can set the renderer to something other than the default, including MathML. It will warn you that MathML may not fully work.
So knowing MathML syntax won’t help you use MathJax. Its syntax is \LaTeX as Dr.S mentions.
Thank you both! D’oh! 
I’ve screwed that up twice now in sperate threads / posts.
The editor I use does MathML & LaTeX with the flip of a switch. I only use the LaTeX side. But the the damned thing is titled “MathML” whichever way you flip the switch. So I keep falling for that head-fake and get the terminology backwards.
Yes, yes, I ought to at least recognize that ML means mark-up language and sorta implies a <whatever> sort of syntax.
Thank you again. LaTeX LaTeX LaTeX !!!11!1!
That’s \LaTeX, good sir!
I guess my beatings will continue until I get it right! 
LaTeX is permissible in text in the absence of \LaTeX.
I go back to the days of \TeX, before \LaTeX. For my own purposes, I’ve written a Javascript (limited) \LaTeX to MathML converter, so I’ve had to become somewhat familiar with how various browsers do or do not handle MathML.
Nope, that is for morale, not getting things right.
\\tan Zn = \\frac {\\sin LHA}{\\cos LHA \\sin L - \\cos L \\tan d}
Testing these 2…
•
And, in a list?
And, in a list?
You may not have noticed this, but if you put 1 or more emoticons on a line with no other characters, including no whitespace, they come out large:
But if you put any other characters on the same line, they come out small:
I slipped a Space in between them just above.
A trailing space won’t work to trigger small, but a trailing AKA non-breaking space will trigger small without messing up the visible spacing. Compare space between with nbsp at the end:
Emoticons work fine in lists; they’re just another character from Discourse’s POV.
- blah
- blah2
blah3
Multiple replies
★ ➙ ➞ blah blah blah #1
★ ➙ ➞ blah blah blah #2
★ ➙ ➞ blah blah blah #3
★ ➙ ➞ blah blah blah #4
Okay I’ll try that in a coming post.
Well, that didn’t work.
(tried to blur text within a poll)
Interesting. It works in Markdown preview mode or WYSIWYG editor mode but not in the real post.
Nm
Never you mind.
