xFormula 3.1 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The program lies within Education Tools, more precisely Science. We recommend checking the downloaded files with any free antivirus. The actual developer of this free Mac application is Xu Zhang.
From the developer:
xFormula is a math equation editor with the ability to export the result as image, LaTeX. The application include variables, binary operators, arrows, relations, brackets, underline, overline, accents, fraction, radical, large operator, and everything you need for both simple and complex equations.
You may want to check out more Mac applications, such as MacSpice, Periodic Table or Mercury, which might be related to xFormula.