  Here we define a procedure for evaluating KL-projections (I- and
rI-projections) of channels. These can be useful in the decomposition of mutual
information between input and outputs, e.g. to quantify synergies and
interactions of different orders, as well as information integration and other
related measures of complexity.
  The algorithm is a generalization of the standard iterative scaling
algorithm, which we here extend from probability distributions to channels
(also known as transition kernels).
