What is harmonic entropy?

It's well documented on the Xenharmonic wiki.

There is a certain tolerance for frequency difference -- if two frequencies are close enough, then to human ears they should be equivalent. Maybe we could define this as: at least close enough so that their "beat" frequency is no faster than 1 Hz. Probably need to investigate / play around with this idea further.

1. Define a multi-valued time series of fundamental frequencies (a.k.a. "sine wave music"). Each frequency corresponds to an oscillator to which we later add a certain overtone series.
2. Choose a set of discrete intervals over which to do the harmonic analysis and optimization. Aside It may be possible to do a continuous-time optimization -- i.e. continuous optimal control.
3. Apply perturbations to each fundamental's harmonic series -- i.e. perturb the oscillator shape

PROBLEM Adjusting the overtones in the harmonic series -- even a tiny amount -- really sound pretty awful.

4. For each interval (for which the fundamentals may have different harmonic relationships) apply a set of optimization criteria to adjust the oscillator shapes so that the overtone series' This is the hard part. There are many optimization goals that could be implemented here. Here are some ideas:

• penalize non-decaying overtone series
• penalize distance from original perturbed values
• penalize harmonic entropy