[rahimiali]

the matrix example is a good example of latex being too verbose for its markdown host. \underbrace and \begin{cases} are two others ones that seems antithetical to markdown. and maybe the fact that \left[ and \left( are not the default versions of [ and ( respectively. i'd be interested in collecting more if you can think of them.

[runarberg]

I collected some in the doc page for mathup (link in cousin post). Although I’m not sure I tackled \underbrace sufficiently. E.g. This is how I explain up-arrow notion with a mathup expression:

    obrace(a\`↑↑`b = ubrace(a^a^⋰^a)._(b  "times")).^"" "up-arrow" notation ""

I don’t think you’ll be able to read this without knowing some of the syntax... which is a failure on my part as author. `obrace` and ubrace` are clear `.^` puts the following expression (a text that works the same way as backticks in markdown) over the preceding expression. `._` does the same but puts it under. and the backslash will make the thing surrounded by backticks (\`↑↑`) an operator. But this is a fairly complected expression. And my goal was never to make every expression look simple. A far more common expression would be easier:

    a^n = obrace(a xx a xx cdots xx a).^(n  "times")

which could also be written as:

    a^n = (a × a × ⋯ × a).^⏞.^(n  "times")

Regarding cases, in mathup could write:

    n! = { 1,      if n <= 1
           (n-1)!, otherwise

However the alignment won’t be perfect... I was always going to go back and fix that, but I never got around to do that.

Other improvements include, using white space smartly to group things together e.g. (This example also showcases using slash to denote fraction)

    a/b + c/d != a / b+c / d