  Multi-degree splines are smooth piecewise-polynomial functions where the
pieces can have different degrees. We describe a simple algorithmic
construction of a set of basis functions for the space of multi-degree splines,
with similar properties to standard B-splines. These basis functions are called
multi-degree B-splines (or MDB-splines). The construction relies on an
extraction operator that represents all MDB-splines as linear combinations of
local B-splines of different degrees. This enables the use of existing
efficient algorithms for B-spline evaluations and refinements in the context of
multi-degree splines. A Matlab implementation is provided to illustrate the
computation and use of MDB-splines.
