creaktive/c5.pl

## c5.pl
#!/usr/bin/env perl
# inspired by https://randscullard.com/CircleOfFifths/
# and http://pages.mtu.edu/~suits/notefreqs.html
use 5.010;
use strict;
use warnings;

use charnames ();
use open OUT => ':locale';
use utf8;

my $tones   = 12;
my @mode    = qw( 2 2 1 2 2 2 1 ); # Ionian
# my @mode    = qw( 2 1 2 2 1 2 2 ); # Aeolian
my %natural = qw( 0 C 2 D 4 E 5 F 7 G 9 A 11 B );

my @note;
my $c = 0;
for my $i ( @mode ) {
    push @note => $c;
    $c += $i;
}

my ( %sharp, %flat );
for my $i ( keys %natural ) {
    $sharp { ( $i + 1 ) % $tones } = $natural{ $i } . "\N{MUSIC SHARP SIGN}";
    $flat  { ( $i - 1 ) % $tones } = $natural{ $i } . "\N{MUSIC FLAT SIGN}";
}

sub print_scale (@) { sprintf join( ' ', ( '%-2s' ) x 7 ) => @_ }
sub notes ($) { map { ( 7 * $_[ 0 ] + $note[ $_ ] ) % $tones } 0 .. $#mode }

for my $i ( 0 .. 6 ) {
    say print_scale map {
        $i == 6
            ? $sharp{ $_ }   || $natural{ $_ }
            : $natural{ $_ } || $sharp{ $_ }
    } notes $i
}

for my $i ( 6 .. 11 ) {
    say print_scale map {
        $i == 6
            ? $flat{ $_ }    || $natural{ $_ }
            : $natural{ $_ } || $flat{ $_ }
    } notes $i
}

__DATA__
C  D  E  F  G  A  B
G  A  B  C  D  E  F♯
D  E  F♯ G  A  B  C♯
A  B  C♯ D  E  F♯ G♯
E  F♯ G♯ A  B  C♯ D♯
B  C♯ D♯ E  F♯ G♯ A♯
F♯ G♯ A♯ B  C♯ D♯ E♯
G♭ A♭ B♭ C♭ D♭ E♭ F
D♭ E♭ F  G♭ A♭ B♭ C
A♭ B♭ C  D♭ E♭ F  G
E♭ F  G  A♭ B♭ C  D
B♭ C  D  E♭ F  G  A
F  G  A  B♭ C  D  E

## circle-of-filth.html
<!doctype html>
<html class="no-js" lang="">
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
        <title>Major & Minor Scales</title>
        <meta name="description" content="">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <link href="https://fonts.googleapis.com/css?family=Source+Code+Pro:200" rel="stylesheet">
        <style>
            body { background-color: #000 }
            table {
                border: 0;
                -webkit-border-horizontal-spacing: 0;
                -webkit-border-vertical-spacing: 0;
            }
            td {
                width: 10em;
                height: 10em;
                color: #fff;
                font-family: 'Source Code Pro', monospace;
                font-size: 10pt;
                text-align: center;
                vertical-align: middle;
            }
            td span { opacity: 0.75 }
            td span big { font-size: 3em }
        </style>
    </head>
    <body><table>

	<tr>
		<td style="background-color:#9A0000"><span><big>C♯</big><br/>277.2 Hz<br/>124.5 cm</span></td>
		<td style="background-color:#FF0000"><span><big>D♯</big><br/>311.1 Hz<br/>110.9 cm</span></td>
		<td style="background-color:#FF5300"><span><big>F</big><br/>349.2 Hz<br/>98.8 cm</span></td>
		<td style="background-color:#FFD400"><span><big>F♯</big><br/>370.0 Hz<br/>93.2 cm</span></td>
		<td style="background-color:#20FF00"><span><big>G♯</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#4800FF"><span><big>A♯</big><br/>466.2 Hz<br/>74.0 cm</span></td>
		<td style="background-color:#610000"><span><big>C</big><br/>523.3 Hz<br/>65.9 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#FFD400"><span><big>F♯</big><br/>370.0 Hz<br/>93.2 cm</span></td>
		<td style="background-color:#20FF00"><span><big>G♯</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#4800FF"><span><big>A♯</big><br/>466.2 Hz<br/>74.0 cm</span></td>
		<td style="background-color:#610061"><span><big>B</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>C♯</big><br/>554.4 Hz<br/>62.2 cm</span></td>
		<td style="background-color:#FF0000"><span><big>D♯</big><br/>622.3 Hz<br/>55.4 cm</span></td>
		<td style="background-color:#FF5300"><span><big>F</big><br/>698.5 Hz<br/>49.4 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#610061"><span><big>B</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>C♯</big><br/>554.4 Hz<br/>62.2 cm</span></td>
		<td style="background-color:#FF0000"><span><big>D♯</big><br/>622.3 Hz<br/>55.4 cm</span></td>
		<td style="background-color:#FF0000"><span><big>E</big><br/>659.3 Hz<br/>52.3 cm</span></td>
		<td style="background-color:#FFD400"><span><big>F♯</big><br/>740.0 Hz<br/>46.6 cm</span></td>
		<td style="background-color:#20FF00"><span><big>G♯</big><br/>830.6 Hz<br/>41.5 cm</span></td>
		<td style="background-color:#4800FF"><span><big>A♯</big><br/>932.3 Hz<br/>37.0 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#FF0000"><span><big>E</big><br/>329.6 Hz<br/>104.7 cm</span></td>
		<td style="background-color:#FFD400"><span><big>F♯</big><br/>370.0 Hz<br/>93.2 cm</span></td>
		<td style="background-color:#20FF00"><span><big>G♯</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>A</big><br/>440.0 Hz<br/>78.4 cm</span></td>
		<td style="background-color:#610061"><span><big>B</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>C♯</big><br/>554.4 Hz<br/>62.2 cm</span></td>
		<td style="background-color:#FF0000"><span><big>D♯</big><br/>622.3 Hz<br/>55.4 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#00B6FF"><span><big>A</big><br/>440.0 Hz<br/>78.4 cm</span></td>
		<td style="background-color:#610061"><span><big>B</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>C♯</big><br/>554.4 Hz<br/>62.2 cm</span></td>
		<td style="background-color:#D20000"><span><big>D</big><br/>587.3 Hz<br/>58.7 cm</span></td>
		<td style="background-color:#FF0000"><span><big>E</big><br/>659.3 Hz<br/>52.3 cm</span></td>
		<td style="background-color:#FFD400"><span><big>F♯</big><br/>740.0 Hz<br/>46.6 cm</span></td>
		<td style="background-color:#20FF00"><span><big>G♯</big><br/>830.6 Hz<br/>41.5 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#D20000"><span><big>D</big><br/>293.7 Hz<br/>117.5 cm</span></td>
		<td style="background-color:#FF0000"><span><big>E</big><br/>329.6 Hz<br/>104.7 cm</span></td>
		<td style="background-color:#FFD400"><span><big>F♯</big><br/>370.0 Hz<br/>93.2 cm</span></td>
		<td style="background-color:#B5FF00"><span><big>G</big><br/>392.0 Hz<br/>88.0 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>A</big><br/>440.0 Hz<br/>78.4 cm</span></td>
		<td style="background-color:#610061"><span><big>B</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>C♯</big><br/>554.4 Hz<br/>62.2 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#B5FF00"><span><big>G</big><br/>392.0 Hz<br/>88.0 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>A</big><br/>440.0 Hz<br/>78.4 cm</span></td>
		<td style="background-color:#610061"><span><big>B</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#610000"><span><big>C</big><br/>523.3 Hz<br/>65.9 cm</span></td>
		<td style="background-color:#D20000"><span><big>D</big><br/>587.3 Hz<br/>58.7 cm</span></td>
		<td style="background-color:#FF0000"><span><big>E</big><br/>659.3 Hz<br/>52.3 cm</span></td>
		<td style="background-color:#FFD400"><span><big>F♯</big><br/>740.0 Hz<br/>46.6 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#610000"><span><big>C</big><br/>261.6 Hz<br/>131.9 cm</span></td>
		<td style="background-color:#D20000"><span><big>D</big><br/>293.7 Hz<br/>117.5 cm</span></td>
		<td style="background-color:#FF0000"><span><big>E</big><br/>329.6 Hz<br/>104.7 cm</span></td>
		<td style="background-color:#FF5300"><span><big>F</big><br/>349.2 Hz<br/>98.8 cm</span></td>
		<td style="background-color:#B5FF00"><span><big>G</big><br/>392.0 Hz<br/>88.0 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>A</big><br/>440.0 Hz<br/>78.4 cm</span></td>
		<td style="background-color:#610061"><span><big>B</big><br/>493.9 Hz<br/>69.9 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#FF5300"><span><big>F</big><br/>349.2 Hz<br/>98.8 cm</span></td>
		<td style="background-color:#B5FF00"><span><big>G</big><br/>392.0 Hz<br/>88.0 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>A</big><br/>440.0 Hz<br/>78.4 cm</span></td>
		<td style="background-color:#4800FF"><span><big>B♭</big><br/>466.2 Hz<br/>74.0 cm</span></td>
		<td style="background-color:#610000"><span><big>C</big><br/>523.3 Hz<br/>65.9 cm</span></td>
		<td style="background-color:#D20000"><span><big>D</big><br/>587.3 Hz<br/>58.7 cm</span></td>
		<td style="background-color:#FF0000"><span><big>E</big><br/>659.3 Hz<br/>52.3 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#4800FF"><span><big>B♭</big><br/>466.2 Hz<br/>74.0 cm</span></td>
		<td style="background-color:#610000"><span><big>C</big><br/>523.3 Hz<br/>65.9 cm</span></td>
		<td style="background-color:#D20000"><span><big>D</big><br/>587.3 Hz<br/>58.7 cm</span></td>
		<td style="background-color:#FF0000"><span><big>E♭</big><br/>622.3 Hz<br/>55.4 cm</span></td>
		<td style="background-color:#FF5300"><span><big>F</big><br/>698.5 Hz<br/>49.4 cm</span></td>
		<td style="background-color:#B5FF00"><span><big>G</big><br/>784.0 Hz<br/>44.0 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>A</big><br/>880.0 Hz<br/>39.2 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#FF0000"><span><big>E♭</big><br/>311.1 Hz<br/>110.9 cm</span></td>
		<td style="background-color:#FF5300"><span><big>F</big><br/>349.2 Hz<br/>98.8 cm</span></td>
		<td style="background-color:#B5FF00"><span><big>G</big><br/>392.0 Hz<br/>88.0 cm</span></td>
		<td style="background-color:#20FF00"><span><big>A♭</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#4800FF"><span><big>B♭</big><br/>466.2 Hz<br/>74.0 cm</span></td>
		<td style="background-color:#610000"><span><big>C</big><br/>523.3 Hz<br/>65.9 cm</span></td>
		<td style="background-color:#D20000"><span><big>D</big><br/>587.3 Hz<br/>58.7 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#20FF00"><span><big>A♭</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#4800FF"><span><big>B♭</big><br/>466.2 Hz<br/>74.0 cm</span></td>
		<td style="background-color:#610000"><span><big>C</big><br/>523.3 Hz<br/>65.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>D♭</big><br/>554.4 Hz<br/>62.2 cm</span></td>
		<td style="background-color:#FF0000"><span><big>E♭</big><br/>622.3 Hz<br/>55.4 cm</span></td>
		<td style="background-color:#FF5300"><span><big>F</big><br/>698.5 Hz<br/>49.4 cm</span></td>
		<td style="background-color:#B5FF00"><span><big>G</big><br/>784.0 Hz<br/>44.0 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#9A0000"><span><big>D♭</big><br/>277.2 Hz<br/>124.5 cm</span></td>
		<td style="background-color:#FF0000"><span><big>E♭</big><br/>311.1 Hz<br/>110.9 cm</span></td>
		<td style="background-color:#FF5300"><span><big>F</big><br/>349.2 Hz<br/>98.8 cm</span></td>
		<td style="background-color:#FFD400"><span><big>G♭</big><br/>370.0 Hz<br/>93.2 cm</span></td>
		<td style="background-color:#20FF00"><span><big>A♭</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#4800FF"><span><big>B♭</big><br/>466.2 Hz<br/>74.0 cm</span></td>
		<td style="background-color:#610000"><span><big>C</big><br/>523.3 Hz<br/>65.9 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#FFD400"><span><big>G♭</big><br/>370.0 Hz<br/>93.2 cm</span></td>
		<td style="background-color:#20FF00"><span><big>A♭</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#4800FF"><span><big>B♭</big><br/>466.2 Hz<br/>74.0 cm</span></td>
		<td style="background-color:#610061"><span><big>B</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>D♭</big><br/>554.4 Hz<br/>62.2 cm</span></td>
		<td style="background-color:#FF0000"><span><big>E♭</big><br/>622.3 Hz<br/>55.4 cm</span></td>
		<td style="background-color:#FF5300"><span><big>F</big><br/>698.5 Hz<br/>49.4 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#610061"><span><big>B</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>D♭</big><br/>554.4 Hz<br/>62.2 cm</span></td>
		<td style="background-color:#FF0000"><span><big>E♭</big><br/>622.3 Hz<br/>55.4 cm</span></td>
		<td style="background-color:#FF0000"><span><big>E</big><br/>659.3 Hz<br/>52.3 cm</span></td>
		<td style="background-color:#FFD400"><span><big>G♭</big><br/>740.0 Hz<br/>46.6 cm</span></td>
		<td style="background-color:#20FF00"><span><big>A♭</big><br/>830.6 Hz<br/>41.5 cm</span></td>
		<td style="background-color:#4800FF"><span><big>B♭</big><br/>932.3 Hz<br/>37.0 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#9A0000"><span><big>c♯</big><br/>277.2 Hz<br/>124.5 cm</span></td>
		<td style="background-color:#FF0000"><span><big>d♯</big><br/>311.1 Hz<br/>110.9 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e</big><br/>329.6 Hz<br/>104.7 cm</span></td>
		<td style="background-color:#FFD400"><span><big>f♯</big><br/>370.0 Hz<br/>93.2 cm</span></td>
		<td style="background-color:#20FF00"><span><big>g♯</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>a</big><br/>440.0 Hz<br/>78.4 cm</span></td>
		<td style="background-color:#610061"><span><big>b</big><br/>493.9 Hz<br/>69.9 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#FFD400"><span><big>f♯</big><br/>370.0 Hz<br/>93.2 cm</span></td>
		<td style="background-color:#20FF00"><span><big>g♯</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>a</big><br/>440.0 Hz<br/>78.4 cm</span></td>
		<td style="background-color:#610061"><span><big>b</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>c♯</big><br/>554.4 Hz<br/>62.2 cm</span></td>
		<td style="background-color:#D20000"><span><big>d</big><br/>587.3 Hz<br/>58.7 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e</big><br/>659.3 Hz<br/>52.3 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#610061"><span><big>b</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>c♯</big><br/>554.4 Hz<br/>62.2 cm</span></td>
		<td style="background-color:#D20000"><span><big>d</big><br/>587.3 Hz<br/>58.7 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e</big><br/>659.3 Hz<br/>52.3 cm</span></td>
		<td style="background-color:#FFD400"><span><big>f♯</big><br/>740.0 Hz<br/>46.6 cm</span></td>
		<td style="background-color:#B5FF00"><span><big>g</big><br/>784.0 Hz<br/>44.0 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>a</big><br/>880.0 Hz<br/>39.2 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#FF0000"><span><big>e</big><br/>329.6 Hz<br/>104.7 cm</span></td>
		<td style="background-color:#FFD400"><span><big>f♯</big><br/>370.0 Hz<br/>93.2 cm</span></td>
		<td style="background-color:#B5FF00"><span><big>g</big><br/>392.0 Hz<br/>88.0 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>a</big><br/>440.0 Hz<br/>78.4 cm</span></td>
		<td style="background-color:#610061"><span><big>b</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#610000"><span><big>c</big><br/>523.3 Hz<br/>65.9 cm</span></td>
		<td style="background-color:#D20000"><span><big>d</big><br/>587.3 Hz<br/>58.7 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#00B6FF"><span><big>a</big><br/>440.0 Hz<br/>78.4 cm</span></td>
		<td style="background-color:#610061"><span><big>b</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#610000"><span><big>c</big><br/>523.3 Hz<br/>65.9 cm</span></td>
		<td style="background-color:#D20000"><span><big>d</big><br/>587.3 Hz<br/>58.7 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e</big><br/>659.3 Hz<br/>52.3 cm</span></td>
		<td style="background-color:#FF5300"><span><big>f</big><br/>698.5 Hz<br/>49.4 cm</span></td>
		<td style="background-color:#B5FF00"><span><big>g</big><br/>784.0 Hz<br/>44.0 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#D20000"><span><big>d</big><br/>293.7 Hz<br/>117.5 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e</big><br/>329.6 Hz<br/>104.7 cm</span></td>
		<td style="background-color:#FF5300"><span><big>f</big><br/>349.2 Hz<br/>98.8 cm</span></td>
		<td style="background-color:#B5FF00"><span><big>g</big><br/>392.0 Hz<br/>88.0 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>a</big><br/>440.0 Hz<br/>78.4 cm</span></td>
		<td style="background-color:#4800FF"><span><big>b♭</big><br/>466.2 Hz<br/>74.0 cm</span></td>
		<td style="background-color:#610000"><span><big>c</big><br/>523.3 Hz<br/>65.9 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#B5FF00"><span><big>g</big><br/>392.0 Hz<br/>88.0 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>a</big><br/>440.0 Hz<br/>78.4 cm</span></td>
		<td style="background-color:#4800FF"><span><big>b♭</big><br/>466.2 Hz<br/>74.0 cm</span></td>
		<td style="background-color:#610000"><span><big>c</big><br/>523.3 Hz<br/>65.9 cm</span></td>
		<td style="background-color:#D20000"><span><big>d</big><br/>587.3 Hz<br/>58.7 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e♭</big><br/>622.3 Hz<br/>55.4 cm</span></td>
		<td style="background-color:#FF5300"><span><big>f</big><br/>698.5 Hz<br/>49.4 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#610000"><span><big>c</big><br/>261.6 Hz<br/>131.9 cm</span></td>
		<td style="background-color:#D20000"><span><big>d</big><br/>293.7 Hz<br/>117.5 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e♭</big><br/>311.1 Hz<br/>110.9 cm</span></td>
		<td style="background-color:#FF5300"><span><big>f</big><br/>349.2 Hz<br/>98.8 cm</span></td>
		<td style="background-color:#B5FF00"><span><big>g</big><br/>392.0 Hz<br/>88.0 cm</span></td>
		<td style="background-color:#20FF00"><span><big>a♭</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#4800FF"><span><big>b♭</big><br/>466.2 Hz<br/>74.0 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#FF5300"><span><big>f</big><br/>349.2 Hz<br/>98.8 cm</span></td>
		<td style="background-color:#B5FF00"><span><big>g</big><br/>392.0 Hz<br/>88.0 cm</span></td>
		<td style="background-color:#20FF00"><span><big>a♭</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#4800FF"><span><big>b♭</big><br/>466.2 Hz<br/>74.0 cm</span></td>
		<td style="background-color:#610000"><span><big>c</big><br/>523.3 Hz<br/>65.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>d♭</big><br/>554.4 Hz<br/>62.2 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e♭</big><br/>622.3 Hz<br/>55.4 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#4800FF"><span><big>b♭</big><br/>466.2 Hz<br/>74.0 cm</span></td>
		<td style="background-color:#610000"><span><big>c</big><br/>523.3 Hz<br/>65.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>d♭</big><br/>554.4 Hz<br/>62.2 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e♭</big><br/>622.3 Hz<br/>55.4 cm</span></td>
		<td style="background-color:#FF5300"><span><big>f</big><br/>698.5 Hz<br/>49.4 cm</span></td>
		<td style="background-color:#FFD400"><span><big>g♭</big><br/>740.0 Hz<br/>46.6 cm</span></td>
		<td style="background-color:#20FF00"><span><big>a♭</big><br/>830.6 Hz<br/>41.5 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#FF0000"><span><big>e♭</big><br/>311.1 Hz<br/>110.9 cm</span></td>
		<td style="background-color:#FF5300"><span><big>f</big><br/>349.2 Hz<br/>98.8 cm</span></td>
		<td style="background-color:#FFD400"><span><big>g♭</big><br/>370.0 Hz<br/>93.2 cm</span></td>
		<td style="background-color:#20FF00"><span><big>a♭</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#4800FF"><span><big>b♭</big><br/>466.2 Hz<br/>74.0 cm</span></td>
		<td style="background-color:#610061"><span><big>b</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>d♭</big><br/>554.4 Hz<br/>62.2 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#20FF00"><span><big>a♭</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#4800FF"><span><big>b♭</big><br/>466.2 Hz<br/>74.0 cm</span></td>
		<td style="background-color:#610061"><span><big>b</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>d♭</big><br/>554.4 Hz<br/>62.2 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e♭</big><br/>622.3 Hz<br/>55.4 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e</big><br/>659.3 Hz<br/>52.3 cm</span></td>
		<td style="background-color:#FFD400"><span><big>g♭</big><br/>740.0 Hz<br/>46.6 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#9A0000"><span><big>d♭</big><br/>277.2 Hz<br/>124.5 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e♭</big><br/>311.1 Hz<br/>110.9 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e</big><br/>329.6 Hz<br/>104.7 cm</span></td>
		<td style="background-color:#FFD400"><span><big>g♭</big><br/>370.0 Hz<br/>93.2 cm</span></td>
		<td style="background-color:#20FF00"><span><big>a♭</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>a</big><br/>440.0 Hz<br/>78.4 cm</span></td>
		<td style="background-color:#610061"><span><big>b</big><br/>493.9 Hz<br/>69.9 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#FFD400"><span><big>g♭</big><br/>370.0 Hz<br/>93.2 cm</span></td>
		<td style="background-color:#20FF00"><span><big>a♭</big><br/>415.3 Hz<br/>83.1 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>a</big><br/>440.0 Hz<br/>78.4 cm</span></td>
		<td style="background-color:#610061"><span><big>b</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>d♭</big><br/>554.4 Hz<br/>62.2 cm</span></td>
		<td style="background-color:#D20000"><span><big>d</big><br/>587.3 Hz<br/>58.7 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e</big><br/>659.3 Hz<br/>52.3 cm</span></td>
	</tr>
	<tr>
		<td style="background-color:#610061"><span><big>b</big><br/>493.9 Hz<br/>69.9 cm</span></td>
		<td style="background-color:#9A0000"><span><big>d♭</big><br/>554.4 Hz<br/>62.2 cm</span></td>
		<td style="background-color:#D20000"><span><big>d</big><br/>587.3 Hz<br/>58.7 cm</span></td>
		<td style="background-color:#FF0000"><span><big>e</big><br/>659.3 Hz<br/>52.3 cm</span></td>
		<td style="background-color:#FFD400"><span><big>g♭</big><br/>740.0 Hz<br/>46.6 cm</span></td>
		<td style="background-color:#B5FF00"><span><big>g</big><br/>784.0 Hz<br/>44.0 cm</span></td>
		<td style="background-color:#00B6FF"><span><big>a</big><br/>880.0 Hz<br/>39.2 cm</span></td>
	</tr>
    </table></body>
</html>


## circle-of-filth.pl
#!/usr/bin/env perl
# inspired by https://randscullard.com/CircleOfFifths/
# and http://pages.mtu.edu/~suits/notefreqs.html
use 5.010;
use strict;
use warnings;

use charnames ();
use open OUT => ':locale';
use utf8;

use Carp;
use POSIX;
use Scalar::Util qw(dualvar);

my $tones = 12;
my %notes = qw(0 C 2 D 4 E 5 F 7 G 9 A 11 B);
my @freqs =
    map { 2 ** (($_ - 9) / $tones) * 440 }
    0 .. $tones - 1;
my @wavelengths =  map { 345 / $_ } @freqs;
my @rgb = reverse map {
        sprintf '#' . ('%02X' x 3),
            map { POSIX::round(255 * $_) }
            convert_wave_length_nm_to_rgb($_)
    } map {
        380 + 400 * $_      # in nanometers
    } map {
        ($_ - $wavelengths[0]) / ($wavelengths[-1] - $wavelengths[0])
    } @wavelengths;
my $last_note;
my @sharps;
for my $i (0 .. $tones - 1) {
    push   @sharps, dualvar $i, $notes{$i} // $last_note . "\N{MUSIC SHARP SIGN}";
    $last_note = $notes{$i};
}
my @flats;
for my $i (reverse 0 .. $tones - 1) {
    unshift @flats, dualvar $i, =>  $notes{$i} // $last_note . "\N{MUSIC FLAT SIGN}";
    $last_note = $notes{$i};
}

my @major = reverse (       # fifths steps
    (map {  $flats[$_ * 7 % $tones] }  3 .. 10),
    (map { $sharps[$_ * 7 % $tones] } 11 .. 29),
);
my @major_order = reverse ( # 5,3,1,6,4,2,0
    (grep { not $_ % 2 } 0 .. 6),
    (grep {     $_ % 2 } 1 .. 5),
);

my @minor = (               # fourths steps
    (map { $sharps[$_ * 5 % $tones] } -2 .. 11),
    (map {  $flats[$_ * 5 % $tones] } 12 .. 24),
);
my @minor_order = @major_order[5, 6, 0 .. 4];

say <<'HEADER';
<!doctype html>
<html class="no-js" lang="">
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
        <title>Major & Minor Scales</title>
        <meta name="description" content="">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <link href="https://fonts.googleapis.com/css?family=Source+Code+Pro:200" rel="stylesheet">
        <style>
            body { background-color: #000 }
            table {
                border: 0;
                -webkit-border-horizontal-spacing: 0;
                -webkit-border-vertical-spacing: 0;
            }
            td {
                width: 10em;
                height: 10em;
                color: #fff;
                font-family: 'Source Code Pro', monospace;
                font-size: 10pt;
                text-align: center;
                vertical-align: middle;
            }
            td span { opacity: 0.75 }
            td span big { font-size: 3em }
        </style>
    </head>
    <body><table>
HEADER

print_scale(0, (@major[$_ .. $_ + 6]) [@major_order]) for 5 .. 19;
print_scale(1, (@minor[$_ .. $_ + 6]) [@minor_order]) for 5 .. 19;

say <<'FOOTER';
    </table></body>
</html>
FOOTER

sub print_scale {
    my ($is_minor, @scale) = @_;
    my $row = qq(\t\t<td style="background-color:%s"><span><big>%s</big><br/>%0.1f Hz<br/>%0.1f cm</span></td>\n);
    say "\t<tr>";
    my $o = 1;
    my $prev_note;
    for my $note (@scale) {
        ++$o if defined $prev_note && $freqs[$note] < $freqs[$prev_note];
        printf $row,
            $rgb[$note],
            $is_minor ? lc $note : uc $note,
            $o * $freqs[$note],
            ($wavelengths[$note] * 100) / $o;
        $prev_note = $note;
    }
    say "\t</tr>";
}

# Ported to Perl from: https://github.com/ArashPartow/bitmap/blob/master/bitmap_image.hpp
# Credits: Dan Bruton http://www.physics.sfasu.edu/astro/color.html
sub convert_wave_length_nm_to_rgb {
    my ($wave_length_nm, $gamma) = @_;
    $gamma ||= 0.8;

    my ($red, $green, $blue);

    if ((380 <= $wave_length_nm) && ($wave_length_nm < 440)) {
        $red    = -($wave_length_nm - 440) / (440 - 380);
        $green  = 0;
        $blue   = 1;
    } elsif ((440 <= $wave_length_nm) && ($wave_length_nm < 490)) {
        $red    = 0;
        $green  = ($wave_length_nm - 440) / (490 - 440);
        $blue   = 1;
    } elsif ((490 <= $wave_length_nm) && ($wave_length_nm < 510)) {
        $red    = 0;
        $green  = 1;
        $blue   = -($wave_length_nm - 510) / (510 - 490);
    } elsif ((510 <= $wave_length_nm) && ($wave_length_nm < 580)) {
        $red    = ($wave_length_nm - 510) / (580 - 510);
        $green  = 1;
        $blue   = 0;
    } elsif ((580 <= $wave_length_nm) && ($wave_length_nm < 645)) {
        $red    = 1;
        $green  = -($wave_length_nm - 645) / (645 - 580);
        $blue   = 0;
    } elsif ((645 <= $wave_length_nm) && ($wave_length_nm <= 780)) {
        $red    = 1;
        $green  = 0;
        $blue   = 0;
    } else {
        carp "Wave length of $wave_length_nm nm is outside of the visible range (380-780 nm)";
        $red = $green = $blue = 0;
    }

    my $factor;

    if ((380 <= $wave_length_nm) && ($wave_length_nm < 420)) {
        $factor = 0.3 + 0.7 * ($wave_length_nm - 380) / (420 - 380);
    } elsif ((420 <= $wave_length_nm) && ($wave_length_nm < 700)) {
        $factor = 1;
    } elsif ((700 <= $wave_length_nm) && ($wave_length_nm <= 780)) {
        $factor = 0.3 + 0.7 * (780 - $wave_length_nm) / (780 - 700);
    } else {
        $factor = 0;
    }

    return map {
        ($_ * $factor) ** $gamma
    } ($red, $green, $blue);
}

__DATA__
C   D   E   F   G   A   B
F   G   A   A♯  C   D   E
A♯  C   D   D♯  F   G   A
D♯  F   G   G♯  A♯  C   D
G♯  A♯  C   C♯  D♯  F   G
C♯  D♯  F   F♯  G♯  A♯  C
F♯  G♯  A♯  B   C♯  D♯  F
B   C♯  D♯  E   F♯  G♯  A♯
E   F♯  G♯  A   B   C♯  D♯
A   B   C♯  D   E   F♯  G♯
D   E   F♯  G   A   B   C♯
G   A   B   C   D   E   F♯
C   D   E   F   G   A   B
F   G   A   B♭  C   D   E
B♭  C   D   E♭  F   G   A
E♭  F   G   A♭  B♭  C   D
A♭  B♭  C   D♭  E♭  F   G
D♭  E♭  F   G♭  A♭  B♭  C
G♭  A♭  B♭  B   D♭  E♭  F
B   D♭  E♭  E   G♭  A♭  B♭
E   G♭  A♭  A   B   D♭  E♭
c   d   d♯  f   g   g♯  a♯
f   g   g♯  a♯  c   c♯  d♯
a♯  c   c♯  d♯  f   f♯  g♯
d♯  f   f♯  g♯  a♯  b   c♯
g♯  a♯  b   c♯  d♯  e   f♯
c♯  d♯  e   f♯  g♯  a   b
f♯  g♯  a   b   c♯  d   e
b   c♯  d   e   f♯  g   a
e   f♯  g   a   b   c   d
a   b   c   d   e   f   g
d   e   f   g   a   b♭  c
g   a   b♭  c   d   e♭  f
c   d   e♭  f   g   a♭  b♭
f   g   a♭  b♭  c   d♭  e♭
b♭  c   d♭  e♭  f   g♭  a♭
e♭  f   g♭  a♭  b♭  b   d♭
a♭  b♭  b   d♭  e♭  e   g♭
d♭  e♭  e   g♭  a♭  a   b
g♭  a♭  a   b   d♭  d   e
b   d♭  d   e   g♭  g   a
e   g♭  g   a   b   c   d
	#!/usr/bin/env perl
	# inspired by https://randscullard.com/CircleOfFifths/
	# and http://pages.mtu.edu/~suits/notefreqs.html
	use 5.010;
	use strict;
	use warnings;

	use charnames ();
	use open OUT => ':locale';
	use utf8;

	my $tones = 12;
	my @mode = qw( 2 2 1 2 2 2 1 ); # Ionian
	# my @mode = qw( 2 1 2 2 1 2 2 ); # Aeolian
	my %natural = qw( 0 C 2 D 4 E 5 F 7 G 9 A 11 B );

	my @note;
	my $c = 0;
	for my $i ( @mode ) {
	push @note => $c;
	$c += $i;
	}

	my ( %sharp, %flat );
	for my $i ( keys %natural ) {
	$sharp { ( $i + 1 ) % $tones } = $natural{ $i } . "\N{MUSIC SHARP SIGN}";
	$flat { ( $i - 1 ) % $tones } = $natural{ $i } . "\N{MUSIC FLAT SIGN}";
	}

	sub print_scale (@) { sprintf join( ' ', ( '%-2s' ) x 7 ) => @_ }
	sub notes ($) { map { ( 7 * $_[ 0 ] + $note[ $_ ] ) % $tones } 0 .. $#mode }

	for my $i ( 0 .. 6 ) {
	say print_scale map {
	$i == 6
	? $sharp{ $_ } \|\| $natural{ $_ }
	: $natural{ $_ } \|\| $sharp{ $_ }
	} notes $i
	}

	for my $i ( 6 .. 11 ) {
	say print_scale map {
	$i == 6
	? $flat{ $_ } \|\| $natural{ $_ }
	: $natural{ $_ } \|\| $flat{ $_ }
	} notes $i
	}

	__DATA__
	C D E F G A B
	G A B C D E F♯
	D E F♯ G A B C♯
	A B C♯ D E F♯ G♯
	E F♯ G♯ A B C♯ D♯
	B C♯ D♯ E F♯ G♯ A♯
	F♯ G♯ A♯ B C♯ D♯ E♯
	G♭ A♭ B♭ C♭ D♭ E♭ F
	D♭ E♭ F G♭ A♭ B♭ C
	A♭ B♭ C D♭ E♭ F G
	E♭ F G A♭ B♭ C D
	B♭ C D E♭ F G A
	F G A B♭ C D E