Sine wave

Sine wave is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Task

Generate a sine wave:

1. you choose the frequency of the wave
2. generate a sine wave for 5 seconds
3. play sound

Go

Works with: Ubuntu 16.04

Go lacks audio support in its standard library and, whilst there are third party packages that could be used, an easier approach is to invoke the SoX utility's 'play' command as was done in the second Kotlin example. <lang go>package main

import (

   "fmt"
   "os/exec"

)

func main() {

   synthType := "sine"
   duration := "5"
   frequency := "440"
   cmd := exec.Command("play", "-n", "synth", duration, synthType, frequency)
   err := cmd.Run()
   if err != nil {
       fmt.Println(err)
   }

}</lang>

Kotlin

Using Java Sound API

<lang scala>// Version 1.2.41

import javax.sound.sampled.AudioFormat import javax.sound.sampled.AudioSystem import kotlin.math.sin import kotlin.math.PI

fun sineWave(frequency: Int, seconds: Int, sampleRate: Int): ByteArray {

   val samples = seconds * sampleRate
   val result = ByteArray(samples)
   val interval = sampleRate.toDouble() / frequency
   for (i in 0 until samples) {
       val angle = 2.0 * PI * i / interval
       result[i] = (sin(angle) * 127).toByte()
   }
   return result

}

fun main(args: Array<String>) {

   val sampleRate = 44000
   val buffer = sineWave(440, 5, sampleRate)
   val format = AudioFormat(sampleRate.toFloat(), 8, 1, true, true)
   val line = AudioSystem.getSourceDataLine(format)
   with (line) {
       open(format)
       start()
       write(buffer, 0, buffer.size)
       drain()
       close()
   }

}</lang>

Invoking SoX

An easier approach invoking the SoX utility's 'play' command which has this stuff built-in. The following was tested on Ubuntu 16.04. <lang scala>// Version 1.2.41

fun main(args:Array<String>) {

   val synthType = "sine"
   val duration = "5"
   val frequency = "440"
   val pb = ProcessBuilder("play", "-n", "synth", duration, synthType, frequency)
   pb.directory(null)
   val proc = pb.start()
   proc.waitFor()

}</lang>

Perl 6

Works with: Rakudo version 2018.04.01

What a horribly underspecified task. Ah well, gives me lots of wiggle room to cheat in various ways.

<lang perl6>my ($rows,$cols) = qx/stty size/.words; my $v = floor $rows / 2; print "\e[H\e[J", 'Generating sine wave of zero amplitude and zero frequency for 5 seconds...',

 "\e[$v;0H", '_' x $cols;

sleep 5; say "\e[H\e[J", 'No?, ok how about this:';

use SVG; my $filename = 'sine.svg'; my $out = open($filename, :w) or die "$!\n"; $out.say: SVG.serialize(

   svg => [
       width => 400, height => 150, style => 'stroke:rgb(0,0,255)',
       :rect[:width<100%>, :height<100%>, :fill<white>],
       :path[ :fill<none>, :d('M0,25 C36.42,25,63.58,125,100,125 M100,125 C136.42,125,163.58,25,200,25 M200,25 C236.42,25,263.58,125,300,125 M300,125 C336.42,125,363.58,25,400,25') ],
   ],

); close $out; say "Sine wave generated to {$filename.IO.absolute}, better open it quickly..."; sleep 5; unlink $filename; say 'Oops, too late.'; say 'Still no? Ok how about:'; shell 'play -n -c1 synth 5.0 sin %-12';</lang>