From: Mischa POSLAWSKY <perl@shiar.org>
Date: Mon, 28 Jan 2013 23:50:24 +0000 (+0100)
Subject: base: common powers of two
X-Git-Tag: v1.6~93
X-Git-Url: http://git.shiar.nl/sheet.git/commitdiff_plain/0e5d1f97871610a20d556c336b486e0b5a69a9e2

base: common powers of two
---

diff --git a/base.plp b/base.plp
index cba5242..f34f36e 100644
--- a/base.plp
+++ b/base.plp
@@ -1,8 +1,8 @@
 <(common.inc.plp)><:
 
 Html({
-	title => 'fractions',
-	version => 'v1.0',
+	title => 'number bases',
+	version => 'v1.1',
 	description => [
 		"Cheat sheets summarising various software programs and standards.",
 	],
@@ -12,22 +12,24 @@ Html({
 	stylesheet => [qw'light dark circus mono red'],
 });
 
+my @cols = (2, 6, 8, 9, 10, 12, 16, 18, 20);
+my @morecols = (2, 3, 4, 6, 8, 9, 10, 12, 16, 18, 20, 24, 32, 36, 64);
+my @char = (0..9, 'A'..'Z', 'a'..'z');
 :>
-<h1>Fractions</h1>
+<h1>Number bases</h1>
 
+<h2>Fractions</h2>
 <table>
 <:
-use Math::BigFloat;
-
-my @cols = (2, 6, 8, 9, 10, 12, 16, 18, 20);
-my $count = 40;
 print '<tr><th>';
 print '<th>', $_ for @cols;
 
-my @char = (0..9, 'A'..'Z', 'a'..'z');
+use Math::BigFloat;
+
+my $count = 40;
 my $places = $count<<1;
 
-sub shownum {
+sub showfrac {
 	my ($num, $radix) = @_;
 
 	my $out = '';
@@ -36,8 +38,10 @@ sub shownum {
 
 ADD_DIGITS:
 	for my $place (1 .. $places) {
+		# add a digit in requested base (left shift)
 		$out .= $char[ $num->blsft(1, $radix) ];
 		$num->bmod(1) or do {
+			# no remaining fractional part
 			$class = $out eq '1' ? 'l5' : $place == 1 ? 'l4' : 'l3';
 			last;
 		};
@@ -62,9 +66,56 @@ for my $n (2 .. $count) {
 	for my $radix (@cols) {
 		my $accuracy = int($places * log($radix) / log(10));
 		Math::BigFloat->accuracy($accuracy);
-		shownum(scalar Math::BigFloat->new(1)->bdiv($n, $accuracy+1), $radix);
+		showfrac(scalar Math::BigFloat->new(1)->bdiv($n, $accuracy+1), $radix);
 	}
 }
 
 :></table>
 
+<hr>
+
+<h2>Duplication</h2>
+<table>
+<:
+use 5.010;
+sub showint {
+	my ($int, $radix) = @_;
+	my @digits;
+	while ($int >= 1) {
+		push @digits, $char[$int % $radix];
+		$int /= $radix;
+	}
+	splice @digits, 3 * $_, 0, '&nbsp;' for reverse 1 .. @digits/3;
+	return join '', reverse @digits;
+}
+
+@cols = grep { not $_ ~~ [2,8,16] } @cols, 36;
+print '<tr><th>';
+print '<th>', $_ for @cols;
+
+for my $n (3 .. 16, 18, 20, 24, 30, 32, 36, 40, 48, 50, 60, 64) {
+	print '<tr>';
+	print '<th>', $n;
+	for my $radix (@cols) {
+		print '<td style="text-align:right">', showint(2 ** $n, $radix);
+	}
+	print '<th>', {
+		 4 => 'nibble',
+		 8 => 'octet',
+		16 => '2o',
+		24 => '3o',
+		32 => '4o',
+		40 => '5o, Tebi',
+		48 => '6o',
+		64 => 'o²',
+		10 => 'kibi',
+		20 => 'Mebi',
+		30 => 'Gibi',
+		50 => 'Pebi',
+		60 => 'Exbi',
+		70 => 'Zebi',
+		80 => 'Yobi',
+	}->{$n} // '';
+}
+
+:></table>