A collection of externals from Iain Mott that mostly provide some math functions for Pure Data:

* polygate~ - switch between multiple signal inputs, variable fade rate both linear & equal power * shuffle - a no-repeat random generator, outputs numbers within a set range * pan~ - equal power stereo panning * system - sends a system message to the console * ln~ - natural log + inverse * rec2pol~ - convert rectangular coordinates to polar eg. can be used to convert sine & cosine rfft~ output to phase & magnitude * pol2rec~ - inverse of rec2pol~ * getenv - Sends value of an environment variable argument on bang