Obake (お化け) [...] are a class of yōkai, preternatural creatures in Japanese folklore. Literally, the terms mean a thing that changes, referring to a state of transformation or shapeshifting.

obake is a C++17 library for the symbolic manipulation of sparse polynomials and other closely-related mathematical objects (e.g., truncated power series, Poisson series, etc.). obake is the successor of the piranha project.

obake is under active development. Preliminary documentation (including installation instructions) is available here.