水素の音

main.go

package main

import (
	"fmt"
	"github.com/go-audio/audio"
	"github.com/go-audio/wav"
	"math"
	"os"
)

func handle(err error) {
	if err != nil {
		panic(err)
	}
}

const (
	sampleRate = 48000
	bitDepth = 16
	length = 10
)

var (
	format = audio.FormatMono48000
)

func main() {
	f, err := os.Create("out.wav")
	handle(err)
	e := wav.NewEncoder(f, sampleRate, bitDepth, 1, 1)

	data := make([]int, sampleRate * length)
	for i := 0; i < sampleRate * length; i++ {
		data[i] = int(multipleRydbergSeries(math.Pow(2, 15)-1, 880, float64(i) / sampleRate))
	}
	fmt.Println(data[:1000])
	buf := &audio.IntBuffer{
		Format:         format,
		Data:           data,
		SourceBitDepth: bitDepth,
	}
	handle(e.Write(buf))
	handle(e.Close())
}

func multipleRydbergSeries(amplitude, baseFreq, t float64) float64 {
	const count = 10
	var f float64
	for i := 1; i <= count; i++ {
		f += rydbergSeries(amplitude, baseFreq, float64(i), t)
	}
	return f / count
}

func rydbergSeries(amplitude, baseFreq, n, t float64) float64 {
	const count = 10
	var f float64
	for i := 1; i <= count; i++ {
		f += rydberg(amplitude, baseFreq, n, n+float64(i), t)
	}
	return f / count
}

func rydberg(amplitude, baseFreq, n1, n2, t float64) float64 {
	return sinWave(amplitude, baseFreq * (1 / n1 / n1 - 1 / n2 / n2), t)
}

func sinWave(amplitude, frequency, t float64) float64 {
	return amplitude * math.Sin(frequency * 2 * math.Pi * t)
}