Mathematical

Quickly convert math equations into beautiful SVGs (or PNGs/MathML).

Mathematical

Installation

Add this line to your application's Gemfile:

gem 'mathematical'

And then execute:

$ bundle

Or install it yourself as:

$ gem install mathematical

Usage

The simplest way to do this is

require 'mathematical'

Mathematical.new.render(string_with_math)

string_with_math should just be a string of math TeX inline ( $..$ ) or display ($$..$$) style math.

The output will be a hash, with keys that depend on the format you want:

If you asked for an SVG, you'll get:
- width: the width of the resulting image
- height: the height of the resulting image
- svg: the actual string of SVG
If you asked for a PNG, you'll get:
- width: the width of the resulting image
- height: the height of the resulting image
- png: the PNG data
If you asked for MathML, you'll get:
- mathml: the MathML data

Note: If you pass in invalid LaTeX, an error is not raised, but a message is printed to STDERR, and the original string is returned (not a hash).

Array of equations

Rather than just a string, you can also provide an array of math inputs:

inputs = []
inputs << '$a$'
inputs << '$b$'
inputs << '$c$'

Mathematical.new.render(inputs)

This returns an array of hashes, possessing the same keys as above.

Note: With an array, it is possible to receive elements that are not hashes. For example, given the following input:

array = ['$foof$', '$not__thisisnotreal$', '$poof$']

You will receive the following output:

Mathematical.new.render(array)
[ {:svg => "...", :width => ... }, '$not__thisisnotreal$', {:svg => "...", :width => ... }]

That is, while the first and last elements are valid LaTeX math, the middle one is not, so the same string is returned. As with a single string, a message is also printed to STDERR.

Options

Mathematical.new takes an optional hash to define a few options:

Name	Description	Default
`:ppi`	A double determining the pixels per inch of the resulting SVG	`72.0`
`:zoom`	A double determining the zoom level of the resulting SVG	`1.0`
`:base64`	A boolean determining whether Mathematical's output should be a base64-encoded SVG string	`false`
`:maxsize`	A numeral indicating the `MAXSIZE` the output string can be.	`unsigned long`
`:format`	A symbol indicating whether you want an `:svg`, `:png`, or `:mathml` output.	`:svg`

Pass these in like this:

opts = { :ppi => 200.0, :zoom => 5.0, :base64 => true }
renderer = Mathematical.new(opts)
renderer.render('$a \ne b$')

Supported commands and symbols

Check out SUPPORTED.md on the mtex2MML website.

Note: This library makes a few assumptions about the strings that you pass in. It assumes that $..$ is inline math and $$..$$ is display math.

Building

Before building this gem, you must install the following libraries:

glib-2.0
gdk-pixbuf-2.0
xml2
cairo
pango

You will also need fonts for cmr10, cmmi10, cmex10, and cmsy10.

Mac install

To install these dependencies on a Mac, everything can be installed via Homebrew:

brew install glib gdk-pixbuf cairo pango

Install the fonts with:

cd ~/Library/Fonts
curl -LO http://mirrors.ctan.org/fonts/cm/ps-type1/bakoma/ttf/cmex10.ttf \
     -LO http://mirrors.ctan.org/fonts/cm/ps-type1/bakoma/ttf/cmmi10.ttf \
     -LO http://mirrors.ctan.org/fonts/cm/ps-type1/bakoma/ttf/cmr10.ttf \
     -LO http://mirrors.ctan.org/fonts/cm/ps-type1/bakoma/ttf/cmsy10.ttf \
     -LO http://mirrors.ctan.org/fonts/cm/ps-type1/bakoma/ttf/esint10.ttf \
     -LO http://mirrors.ctan.org/fonts/cm/ps-type1/bakoma/ttf/eufm10.ttf \
     -LO http://mirrors.ctan.org/fonts/cm/ps-type1/bakoma/ttf/msam10.ttf \
     -LO http://mirrors.ctan.org/fonts/cm/ps-type1/bakoma/ttf/msbm10.ttf \
     -LO http://mirrors.ctan.org/fonts/cm/ps-type1/bakoma/ttf/cmmi10.ttf

xml2 should already be on your machine.

*nix install

To install these dependencies on a *nix machine, fetch the packages through your package manager. For example:

sudo apt-get -qq -y install libglib2.0-dev libxml2-dev libcairo2-dev libpango1.0-dev ttf-lyx libgdk-pixbuf2.0-dev

Windows install

On a Windows machine, I have no idea. Pull requests welcome!

Benchmarks

Benchmarking....
Size: 1164 kilobytes
Iterations: 10
                                               user     system      total        real
Rendering...                             18.070000   0.290000  18.360000 ( 23.003883)

19340 items converted!

Hacking

After cloning the repo:

script/bootstrap
bundle exec rake compile

If there were no errors, you're done! Otherwise, make sure to follow the dependency instructions.

History

There are a smattering of libraries written in various languages to convert math into a variety of formats. But there needs to be a sane way to show math equations in the browser. With browser support for MathML under attack, it's unfortunately not a sustainable solution. A PNG or SVG representation of the equation is the safest way to go.

Most advice suggests using MathJax. While extremely popular I dislike the "stuttering" effect caused by pages loading math. JavaScript shouldn't be used in situations where server-rendering is a possibility, in my opinion.

To that end, I obsessed over the problem of server-side math rendering for over a week. Here was my journey:

I started out with blahtexml, which takes TeX equations and converts them to PNG. This wasn't a bad idea, but it took too long; for twelve equations, it took eight seconds. It was slow because it shelled out to LaTeX, then dvipng.

In fact, as I discovered, most projects on the 'Net shell out to LaTeX, then something else, which makes performance absolutely horrid. I had to find something better, with preferably no dependency on LaTeX.

mimetex was my next attempt. It looked great: a pure C implementation that turned TeX equations into a rasterized representation, and then into a PNG. The speed was there, but the output image was pretty jagged. I tweaked the program to output BMPs, and tried to sharpen those with potrace, but the results were less then pleasant. The "update" to mimetex is mathtex, but it, too, depends on LaTeX and dvipng binaries to produce images.
pmml2svg had potential. It's a set of XSLT stylesheets to convert MathML to SVG. Unfortunately, it relies on XSLT 2.0, of which there are no Ruby bindings (at the time of this writing, April '14). It had to rely on Saxon and Java.
tth converts TeX to HTML, but the output is aesthetically unpleasing, so I passed.
Wikipedia uses texvc, which is written in OCaml, a language I am utterly unfamiliar with. In any event, I could not get the code to compile on my machine.
It took me forever to finally compile gtkmathview, and when it did, I got a bunch of SVG images with screwed up fonts.
dvisvgm worked well, but still depended on two external binaries (LaTeX to convert the text to dvi, and dvisvgm to turn it into SVG)
At one point, I began to try and convert the MathJax code to Ruby to figure out how it accomplished its toSVG methods. The MathJax codebase, while written by geniuses, is incomprehensible, due in part to JavaScript's inability to possess a coherent structure.
Near the end of my wits, I mimicked the behavior of mathrender2, which uses PhantomJS to embed MathJax onto a fake HTML page. This produced exactly what I needed: a bunch of accurate SVG files with no intermediate binaries. It was, unfortunately, a bit slow: for an arbitrary composition of 880 equations, it took about eight seconds to complete. Could I do better?
I came across Lasem, which meet every need. It has no external binary dependencies (only library packages), can convert directly to SVG, and it's fast. The same arbitrary 880 equations were rendered in less than three seconds.

And thus a wrapper was born.

More math stuff

Check out math-to-itex, which quickly parses out TeX notation from strings.

With it, you could do something fun like:

MathToItex(string).convert do |eq, type|
  svg_content = Mathematical.new(:base64 => true).render(eq)

  # create image tags of math with base64-encoded SVGs
  %|<img class="#{type.to_s}-math" data-math-type="#{type.to_s}-math" src="#{svg_content}"/>|
end