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1 change: 1 addition & 0 deletions astro.config.mjs
Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,7 @@ export default defineConfig({
items: [
{ label: 'API', link: '/guides/api/' },
{ label: 'Advanced Use-Cases', link: '/guides/advancedusecases/' },
{ label: 'Customizing MathJS', link: '/guides/custommathjs/' },
],
},
],
Expand Down
56 changes: 56 additions & 0 deletions src/content/docs/guides/customMathJS.md
Original file line number Diff line number Diff line change
@@ -0,0 +1,56 @@
---
title: Customizing MathJS
description: An example on how to import customizations into mathjs
---

You may find yourself wanting to add functionality to the [math view fields](/obsidian-meta-bind-plugin-docs/reference/viewfields/math/).
And as they use [mathjs](https://mathjs.org/) internally, you actually can!

## Importing new options into mathJS

The mathjs library allows the user to define his own functions and constants, as described in [their documentation](https://mathjs.org/docs/core/extension.html).

To leverage that, Meta Bind exposed its mathjs instance for you to modify.
The most sensible place to do this, is inside a [JS-Engine startup-script](/obsidian-js-engine-plugin-docs/guides/startupscripts/).
This ensures the modifications are loaded early and will be immediately available when the first documents gets rendered.

:::caution
Modifying mathJS via a js-engine codeblock inside a document may cause timing problems and is not recommended!
:::

### Adding a custom function `clamp`

As an example, we defined the `clamp()` function, which is not part of default mathJS, but can be very helpful.
It takes in three parameters, the current value, a minimum and a maximum. It returns the current value as long as its inside the range otherwise the boundary-value.

```js
clamp:  (val, min, max) => Math.min(Math.max(min, val), max)
```

Add this definitions inside a JavaScrypt file stored in you Vault and enable that file to be [run as a startup script](/obsidian-js-engine-plugin-docs/guides/startupscripts/).
Inside the file you use the `mathJSimport(dict, options)` function from the API to import you definitions into mathjs.

```js
const mb = engine.getPlugin('obsidian-meta-bind-plugin').api;

mb.mathJSimport({
// we define the function 'clamp'
clamp: (val, min, max) => Math.min(Math.max(min, val), max),

// and a constant 'foo'
foo: 42
});
```

Now you can create a view field using that function.
This example will always display values between 0 and 10, even if `num` gets outside that range.

```meta-bind
VIEW[clamp({num}, 0, 10)]
```

You can also use the new constant `foo`. This will display 52:

```meta-bind
VIEW[foo + 10]
```