  Signals can be interpreted as composed of a rapidly varying component
modulated by a slower varying envelope. Identifying this envelope is an
essential operation in signal processing, with applications in areas ranging
from seismology to medicine. Conventional envelope detection approaches based
on classic methods tend to lack generality, however, and need to be tailored to
each specific application in order to yield reasonable results. Taking
inspiration from geometric concepts, most notably the theory of alpha-shapes,
we introduce a general-purpose library to efficiently extract the envelope of
arbitrary signals.
