Revolution Analytics, a developer of software for computational statistics, has raised $8.6 million in an add-on to its second round of funding, according to a filing with the SEC. Based in Palo Alto, the firm creates software to support users of the open-source R programming language.

Revolution Analytics offers its products to academic institutions for free but charges commercial users for its Revolution R Enterprise product. Clients include Pfizer, Yale Cancer Center and Motorola. Founded in 2007 and formerly called REvolution Computing, the company last raised $9 million in October 2009 from Intel Capital and North Bridge Venture Partners.