// add note about warning when asciimath gem is not available
= AsciiMath Gem
:url-asciimath-repo: https://github.com/asciidoctor/AsciiMath
:stem:

The DocBook toolchain has some support for STEM processing, though it varies depending on which DocBook pipeline you're using and which integrations you have enabled.
But there's one thing we know for sure.
The DocBook toolchain does not understand AsciiMath.
That's where the {url-rubygems}/asciimath[AsciiMath gem^] comes in.

== AsciiMath and DocBook

The AsciiMath gem translates AsciiMath expressions to MathML, which is something the DocBook toolchain is capable of processing.
When the AsciiMath gem is available, the DocBook converter uses it to convert STEM expressions written in AsciiMath notation to MathML and embeds the MathML into the generated DocBook.
Processing the MathML into a displayable format is left up to the DocBook toolchain.

[#install]
== Install

To enable AsciiMath to MathML translation when converting to DocBook, you first need to install the asciimath gem:

 $ gem install asciimath

== Usage

It's not necessary to require the `asciimath` gem explicitly.
As long as the AsciiMath gem is available, the DocBook converter will automatically load and use it to translate AsciiMath notation to MathML.

If the gem is not available, and there's at least one AsciiMath expression in the document, you will see the following message when converting to DocBook:

....
asciidoctor: WARNING: optional gem 'asciimath' is not available. Functionality disabled.
....

The functionality referenced here is the translation from AsciiMath to MathML.
If you see this message, refer back to <<Install>>.

Assuming you have it installed, let's look at an example.

First, activate STEM support in AsciiDoc by setting the `stem` document attribute.
This attribute must be set by the end of the document header.

.Activate STEM support by setting the stem document attribute
[,asciidoc]
----
= Document Title
:stem:

stem:[sqrt(4)] is the square root of 4, which is 2.
----

Now let's convert this document to DocBook using the DocBook converter:

 $ asciidoctor -b docbook asciimath-sample.adoc

The DocBook converter will emit the following XML into the generated document:

[,xml]
----
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msqrt><mml:mn>4</mml:mn></mml:msqrt></mml:math></inlineequation>
----

It's now up to the DocBook toolchain to convert the MathML embedded in the DocBook into a displayable format.
Here's the result you should see:

====
stem:[sqrt(4)] is the square root of 4, which is 2.
====
