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<div class="nb-cell markdown" name="md2">
# Render mathematical formulas

This notebook explains using [Mathjax](https://docs.mathjax.org) in SWISH for rendering formulas in markdown text as well as rendering query answers as formulas.

First of all there is the `mathjax` renderer that renders terms of the form math(String) as mathematical formulas.  Future versions are likely to also render Prolog terms as formulas.  The example below illustrates this renderer.
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<div class="nb-cell program" name="p1">
:- use_rendering(mathjax).
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<div class="nb-cell query" name="q1">
A = math("a^2 + b^2 = c^2").
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<div class="nb-cell markdown" name="md1">
## Using Mathjax in markdown

To use Mathjax in markdown we must provide a _post rendering hook_ for markdown cells.  This hook
is defined by the code fragment below which must appear in an HTML cell somewhere on the notebook.  The fragment loads Mathjax from the CDN network and registers a hook that queues a MathJax request on a markdown cell _after_ the markdown renderer has done the conversion of markdown to HTML.

On this example page the HTML cell holding the code below is the last cell marked _This HTML cell loads Mathjax_.  The text can be omitted to make
the cell invisible, but that also stops the user from opening the cell.

```
&lt;script&gt;
  (function() {
    var nb = notebook;
    require(["https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/MathJax.js"+
             "?config=TeX-MML-AM_CHTML"], function() {
      nb.markdown_post_renderer(function() {
        MathJax.Hub.Queue(["Typeset",MathJax.Hub,this[0]]);
      });
    });
  })();
&lt;/script&gt;
```

### examples

  - The Pythagorean theorem is \(a^2 + b^2 = c^2\).

  - A more chalanging example from [here](https://www.tuhh.de/MathJax/test/sample-tex.html):

    When \(a \ne 0\), there are two solutions to \(ax^2 + bx + c = 0\) and they are
    $$x = {-b \pm \sqrt{b^2-4ac} \over 2a}.$$

## Status

This extension is rather experimental.  Some issues:

  - Mathjax may conflict with markdown.  The Mathjax site suggests some work-arounds but these are not yet implemented.
  - The configuration of Mathjax seems to be global and thus applies to the entire site.
  - Rendering from a string is not ideal.  Eventually we should do such from a Prolog term.
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<div class="nb-cell html" name="htm1">
<hr>
<p style="color:#aaa">This HTML cell loads Mathjax</p>

<script>
  (function() {
    var nb = notebook;
    require(["https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/MathJax.js"+
             "?config=TeX-MML-AM_CHTML"], function() {
      nb.markdown_post_renderer(function() {
        MathJax.Hub.Queue(["Typeset",MathJax.Hub,this[0]]);
      });
    });
  })();
</script>
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