mathurl_helper.rb

require 'mechanize'

module MathUrl
  def mathurl_agent
    @agent ||= WWW::Mechanize.new    
  end
  
  def mathurl_img_for(latex)
    page = math_url_agent.get("http://mathurl.com")
    form = page.forms.first
    # You'll probably want to cache this..
    form.set_field(:latex => latex || %q{ \sin \frac{\pi}{4} = \frac{\sqrt{2}}{2} })
    form.add_field!("make", "make mathURL")
    result = form.submit
    image_url = result.uri.to_s.gsub("/\?", "/\?img=")
    image_tag(image_url)
  end  
end