pyne/pyne — pull request #74 by elliottbiondo (2012-10-29 21:55:18+00:00)
Title: Added MultiMaterial class, mixing functions, and nosetests

A MultiMaterial object has one attribute, _mats, which is a dictionary with Material objects as keys and mass or volume fractions as values. Two member functions, mix_by_mass and mix_by_volume, are used in order to convert the MultiMaterial object into a Material object. Whether mass fractions or volume fractions are used is not implicit within the data structure; it depends which member function is called by the user.

Previously, the plan was to have the MultiMaterial class have member functions that print out materials definitions in many formats (e.g. MCNP, ALARA). However now I think it would make more sense to make these member functions of the Material class.