Don't think "Midi function" is an actual thing. It looks like $f(x) = 440e^{(x-69)/12}$ literally maps the number of a note in the MIDI standard to the actual f

Don't think "Midi function" is an actual thing. It looks like $f(x) = 440e^{(x-69)/12}$ literally maps the number of a note in the MIDI standard to the actual frequency. I guess this question is a bonus to people who paid attention in a particular lecture in class (or who know music and can recognize the significance of 440 and of 12 in the exponent).