• Srap Tasmaner
    4.9k
    Maybe everyone else knew this, but I couldn't figure out the delimiter. It's
    [math][/math]
    



    Those appear to be inline delimiters.

    For comparison, just using Unicode looks like this:

    xFx→⬜∀xFx

    Maybe someone with more expertise than I (@andrewk?) could post (and sticky?) a short primer somewhere.
  • andrewk
    2.1k
    Right-clicking on a piece of latex code brings up a MathJax context menu that includes useful items like
    Show Math As > (choose between mathml and Latex commands); and
    MathJax Help.

    Right-Clicking on the first piece of code above (which is MathJax Latex) gives that, whereas doing it on the second, which is Unicode, does not.

    There is a good primer on physicsforums here.

    MathJax is a Java implementation of LaTeX that interacts with the web browser.Stand-alone LaTeX uses $ and the double-dollar-sign as delimiters for in-line and separate line ('display style') formulas. MathJax implementations usually don't recognise those because that would prevent people from using the $ sign outside of equations.

    physicsforums uses ## as delimiter for in-line but keeps the double dollar sign for display style since one doesn't normally type a double dollar sign in ordinary text.

    As Srap discovered above, the in-line delimiters for this forum are [ math] and [ /math] but without the spaces inside the square brackets (which I inserted here to stop MathJax from interpreting them as delimiters - a classic 'use' vs 'reference' distinction that language philosophers will enjoy).

    I don't know what the delimiters are for display math. I tried a few of the usual things like \[, $$ and [tex] but they didn't work. The forum maintainers would know.
  • jorndoe
    3.6k
    MathJax basic tutorial and quick reference (2016)
    LATEX Tutorials A PRIMER (2003)
    Getting Started with LaTeX (1995) » Mathematical Symbols


    Note, the forums do not support MathJax completely; there are some limitations here and there (e.g. multiple lines of LATEX).


    The Basel problem:



    \sum_{n=1}^\infty \frac{1}{n^2} = \frac{\pi^2}{6}
    


    Function continuity:

    is continuous at



    \forall \epsilon \in \mathbb{R}_{+} \Bigl[ \exists \delta \in \mathbb{R}_{+} \bigl[ \left| x - d \right| < \delta \Rightarrow \left| f(x) - f(d) \right| < \epsilon \bigr] \Bigr]
    


    ... and God said ...



    \begin{aligned} \nabla \times \vec{\mathbf{B}} -\, \frac1c\, \frac{\partial\vec{\mathbf{E}}}{\partial t} & = \frac{4\pi}{c}\vec{\mathbf{j}} \\ \nabla \cdot \vec{\mathbf{E}} & = 4 \pi \rho \\ \nabla \times \vec{\mathbf{E}}\, +\, \frac1c\, \frac{\partial\vec{\mathbf{B}}}{\partial t} & = \vec{\mathbf{0}} \\ \nabla \cdot \vec{\mathbf{B}} & = 0 \end{aligned}
    

    ... and there was light.
  • Srap Tasmaner
    4.9k
    Thanks guys!

    Despite some limitations, should be good enough for our proposes.
  • andrewk
    2.1k
    Based on Jorndoe's post, it appears one can get displaystyle by using the same delimiters
    [math] and [ /math]
    
    .
    and then using the standard latex delimiters for display style inside there, eg

    which used the code
    [math]\begin{align}  \sum_{i=1}^n   r^2  =  r\ \frac{1-r^{n}}{1-r}  \end{align}[/math]
    

    We can tell that it's display style because the subscripts and superscripts for the sum are directly above and below the , instead of to the right of it.

    One thing about MathJax though is that its functioning varies between browsers. My post above looked fine to me when I did it at home this morning on Firefox on Linux, but now, at work on IE in Windows, it interpreted some of the double-dollars as delimiters and made a whole bunch of ordinary text into unreadable pseudo-math. I have fixed that up now so it looks proper on IE-Windows, but I wonder what it will look like from my home computer.
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