Sine wave

Generate a 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

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

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>