package util

import "math"

// Return the frequency of a given MIDI note number.
func NoteFreq(n float64) float64 {
	return (math.Pow(2, (n-69)/12)) * 440
}

// Return the midi note number for the given frequency.
func FreqNote(f float64) float64 {
	return 12*math.Log2(f/440) + 69
}

// Return the one-cent change in frequency at the given frequency.
func CentDeltaFreq(f float64) float64 {
	return f * (math.Pow(2, 1/1200.0) - 1)
}