Plugins | Math - Redactor

Click on a mathematical expression to see the button on the toolbar to edit or insert the expression using the plus button.

<h2>The Relevant Maths</h2>
The reason why some modern physicists think that mathematics has summed the natural numbers actually
has nothing to do with simple algebraic manipulations of the series. So let's take it in stages, and begin
with some much simpler ideas.

$$x = \begin{cases}
 a &\text{if } b \
 c &\text{if } d
\end{cases}$$

In contrast, the ordered sequence $1,\; 1 + 2,\; 1 + 2 + 3, \dots$ has no limit at all
that you can find on a number line. By convention we then say that the sum tends to infinity; although you can't
find infinity on a number line, mathematicians do supplement the number system with a "number" called infinity, and so
it can be said that $1 + 2 + 3 + dots$ equals infinity.

$\overbrace{a+b+c}^{\text{my note}}$

For example, what do we mean by the repeating decimal $0.3333\dots$? This represents the infinite series
$3/10 + 3/100 + 3/1000 + \dots$. It can be shown that the ordered sequence $0.3, 0.33, 0.333, 0.3333, \dots$
converges to 1/3 (or "has a limit of 1/3", or "tends toward 1/3"), and so we define $0.3333\dots$ to equal
1/3. (Technically, that means we can always find an element in that sequence of $0.3, 0.33, 0.333, 0.3333,
\dots$ which is as close to 1/3 as we wish, and such that all successive elements lie even closer to 1/3.) By
the same token, the repeating decimal $0.9999\dots$ equals 1, because the ordered sequence $0.9, 0.99, 0.999, 0.9999, \dots$ converges to 1.

Code

<!DOCTYPE html>
<html>
    <head>
        <title>Redactor</title>
        <meta charset="utf-8">

        <!-- css -->
        <link rel="stylesheet" href="/your-folder/redactor.css" />

        <!-- katex -->
        <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/katex@0.16.9/dist/katex.min.css">
        <script src="https://cdn.jsdelivr.net/npm/katex@0.16.9/dist/katex.min.js"></script>
    </head>
    <body>
        <!-- element -->
        <textarea id="entry">...</textarea>

        <!-- js -->
        <script src="/your-folder/redactor.js"></script>
        <script src="/your-folder/plugins/math/math.js"></script>

        <!-- call -->
        <script>
        Redactor('#entry', {
            plugins: ['math'],
            active: {
                blocks: {
                    'math': ['math']
                }
            }
        });
        </script>
    </body>
</html>

Usage

The plugin supports Katex library by default. To do this, as shown in the example above, you need to connect CSS and JS libraries in your page, like this:


<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/katex@0.16.9/dist/katex.min.css">
<script src="https://cdn.jsdelivr.net/npm/katex@0.16.9/dist/katex.min.js"></script>

By default, the plugin only adds its button to the toolbar. To add it to the context bar, enable the context setting:


Redactor('#entry', {
    plugins: ['math'],
    active: {
        blocks: {
            'math': ['math']
        }
    },
    math: {
        context: true
    }
});