// Calculate how many percent a frequency changes when a vibrato of a certain "cent" (of a semitone - that's the technical term they use) is applied.

// From: https://en.wikipedia.org/wiki/Vibrato
// "The extent of vibrato for solo singers is usually less than a semitone (100 cents) either side of the note"
//   => cent = 100
// "while singers in a choir typically use narrower vibrato with an extent of less than a tenth of a semitone (10 cents) either side"
//   => cent = 10
// "Wind and bowed instruments generally use vibratos with an extent of less than half a semitone either side."
//   => cent = 50

static double vibratoCentToFrequencyPercentage(double cent) {
  ret (plusOneSemitone()-1)*cent;
}