Calculus is utility library which allow to parse some subset of latex equations and store them in Postfix notation It also allows translate it to Abstract syntax tree and calculate (implemented for simple expressions).

Build status: <img src=“http://travis-ci.org/avsej/calculus.png” />

gem install calculus

001:0> require 'calculus'
true
002:0> exp = Calculus::Expression.new("2 + 3 * x")
#<Expression:f46e77a9377ed2d5a9da768496a7e1c20be51bfe postfix_notation=[2, 3, "x", :mul, :plus] variables={"x"=>nil}>
003:0> exp.postfix_notation
[2, 3, "x", :mul, :plus]
004:0> exp.abstract_syntax_tree
[:plus, 2, [:mul, 3, "x"]]
005:0> exp.variables
["x"]
006:0> exp.unbound_variables
["x"]
007:0> exp["x"] = 5
5
008:0> exp.unbound_variables
[]
009:0> exp.calculate
17

You can also render expression to PNG image if you have latex and dvipng installed.

010:0> Calculus::Expression.new("2 + 3 \\cdot x").to_png
"/tmp/d20110512-16457-dhxt71/f46e77a9377ed2d5a9da768496a7e1c20be51bfe.png"

Also you can skip parser if you need only png generation

011:0> Calculus::Expression.new("\\hat{f}(\\xi) = \\int_{-\\infty}^{\\infty} f(x)\\ e^{- 2\\pi i x \\xi}\\,dx", :parse => false).to_png

{hat{f}(xi) = int_{-infty}^{infty} f(x)\ e^{- 2pi i x xi},dx}[]

Don’t forget to cleanup file after using.

Just fork and pull request.