  Existing economic models support the estimation of the costs and benefits of
developing and evolving a Software Product Line (SPL) as compared to
undertaking traditional software development approaches. In addition, Feature
Diagrams (FDs) are a valuable tool to scope the domain of a SPL. This paper
proposes an algorithm to calculate, from a FD, the following information for
economic models: the total number of products of a SPL, the SPL homogeneity and
the commonality of the SPL requirements. The algorithm running time belongs to
the complexity class $O(f^42^c)$. In contrast to related work, the algorithm is
free of dependencies on off-the-self tools and is generally specified for an
abstract FD notation, that works as a pivot language for most of the available
notations for feature modeling.
