def get_element_masses(self, elements=None):
if elements is None:<EOL><INDENT>elements = self.material.elements<EOL><DEDENT>result = numpy.zeros(len(elements))<EOL>for compound in self.material.compounds:<EOL><INDENT>result += self.get_compound_mass(compound) *numpy.array(stoich.element_mass_fractions(compound, elements))<EOL><DEDENT>return result<EOL>
Determine the masses of elements in the package.

:returns: Array of element masses. [kg]