The package offers a collection of useful macros for
disciplines related to signal processing. It defines macros for
plotting a sequence of numbers, drawing the pole-zero diagram
of a system, shading the region of convergence, creating an
adder or a multiplier node, placing a framed node at a given
coordinate, creating an up-sampler or a down-sampler node,
drawing the block diagram of a system, drawing adaptive
systems, sequentially connecting a list of nodes, and
connecting a list of nodes using any node-connecting macro.
