  The complex refractive index m=n+ik of a particle is an intrinsic property
which cannot be directly measured, it must be inferred from its extrinsic
properties such as the scattering and absorption cross-sections. Bohren and
Huffman called this approach describing the dragon from its tracks, since the
inversion of Lorenz-Mie theory equations is intractable without the use of
computers. This article describes PyMieScatt, an open-source module for Python
that contains functionality for solving the inverse problem for complex m using
extensive optical and physical properties as input, and calculating regions
where valid solutions may exist within the error bounds of laboratory
measurements. Additionally, the module has comprehensive capabilities for
studying homogeneous and coated single spheres, as well as ensembles of
homogeneous spheres with user-defined size distributions, making it a complete
tool for studying the optical behavior of spherical particles.
