https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&feedformat=atom&user=Psb777explain xkcd - User contributions [en]2026-04-22T17:33:06ZUser contributionsMediaWiki 1.30.0https://www.explainxkcd.com/wiki/index.php?title=464:_RBA&diff=54627464: RBA2013-12-08T10:18:13Z<p>Psb777: Not yet explained</p>
<hr />
<div>{{comic<br />
| number = 464<br />
| date = August 18, 2008<br />
| title = RBA<br />
| image = rba.png<br />
| titletext = This is a story all about how I started drinking.<br />
}}<br />
<br />
==Explanation==<br />
A "Bel-Air" is an internet meme where a poster on a message board starts a post on a serious topic, but partway through the post switches to repeating the lyrics to the opening theme song of "The Fresh Prince of Bel-Air", a 1990s sitcom starring Will Smith (previously known in his rapping career as the "Fresh Prince") as a street-smart teenager from West Philadelphia who has been sent to live with his affluent and stuffy Aunt and Uncle in Bel Air, Los Angeles by his mother as a consequence of a single altercation with a couple of no-good guys who were making trouble in his previous neighbourhood.<br />
<br />
[[Megan]] in the comic reverses the traditional arrangement by starting the conversation with a recitation of the lyrics to said theme song, and then switching partway through to a very serious discussion of the status of their relationship culminating in a break up.<br />
<br />
The lyrics goes like this<br />
<br />
:Now this is the story all about how <br />
:My life got flipped, turned upside down <br />
:And I'd like to take a minute just sit right there <br />
:I'll tell you how I became ''the prince of a town called Bel-air''<br />
<br />
The title ''RBA'' is an acronym for ''Reverse Bel-Air''.<br />
<br />
OK, but why have they disappeared off stage? And why is the cup dropped?<br />
==Transcript==<br />
:[Megan walks up to Cueball pouring himself a drink.]<br />
:Megan: Now, this is a story all about how<br />
:Megan: My life got flipped turned upside down<br />
:Megan: And I'd like to take a minute<br />
:Megan: Just sit right there<br />
:Megan: I'll tell you how I became uncertain about our relationship. I think you just like having a girlfriend, it doesn't matter who.<br />
:Megan: I think we should break up.<br />
:The reverse Bel-Air only works once, so make it something unforgettable.<br />
:[Cut to dropped glass, drink spilled on ground.]<br />
:Cueball: ...wait, seriously?<br />
:Megan: Yeah.<br />
<br />
{{comic discussion}}<br />
[[Category:Comics featuring Megan]]<br />
[[Category:Comics featuring Cueball]]</div>Psb777https://www.explainxkcd.com/wiki/index.php?title=1292:_Pi_vs._Tau&diff=530401292: Pi vs. Tau2013-11-18T21:15:28Z<p>Psb777: </p>
<hr />
<div>{{comic<br />
| number = 1292<br />
| date = November 17, 2013<br />
| title = Pi vs. Tau<br />
| image = pi vs tau.png<br />
| titletext = Conveniently approximated as e+2, Pau is commonly known as the Devil's Ratio (because in the octal expansion, '666' appears four times in the first 200 digits while no other run of 3+ digits appears more than once.)<br />
}}<br />
<br />
==Explanation==<br />
<br />
This is yet another of Randall's compromise comics. A few mathematicians argue as to whether to use pi, which is the ratio between a circle's circumference and its diameter, or tau, which is the ratio between a circle's circumference and its radius. Randall is suggesting using pau, which is a portmanteau between pi and tau, and is a number situated halfway between pi and tau. This number would be inconvenient, as there are currently no commonly used formulas that involve 1.5 pi or 0.75 tau.<br />
<br />
Some consider pi has being the wrong convention in favor of tau (see the [http://tauday.com/tau-manifesto Tau Manifesto]). Some consider proponents of tau to be foolish and remain loyal to pi (see the [http://www.thepimanifesto.com Pi Manifesto]). Occasionally, the argument is that the food, pi(e), is the whole thing, not half and have made a [http://www.piday.org/ day about it]. Others say on tau day you get twice as much pi(e).<br />
<br />
The inspiration for pi is wrong is found [http://www.math.utah.edu/~palais/pi.html here].<br />
<br />
The trivial nature of the argument is made plain in this comic. Regardless of which convention is used, the fundamental mathematics will remain unaltered<br />
<br />
<br />
The title text for the comic is also incorrect. The first 200 digits of 'pau' in octal are:<br />
<pre><br />
4.5545743763144164432362345144750501224254715730156503147633545270030431677126116550546747570313312523403514716576464333172731124310201076447270723624573721640220437652155065544220143116155742515634462<br />
</pre><br />
The sequence '666' does not occur at all.<br />
<br />
Apparently, [[Randall]] used [http://www.wolframalpha.com/ Wolfram|Alpha] to calculate the result (he uses it a lot, for example [http://what-if.xkcd.com/70/ here] and [http://what-if.xkcd.com/62/ here]).<br />
However, as of 2013-11-18, there's a bug in Wolfram|Alpha so that, when getting 200 octal digits from "pau", it just calculates the decimal value rounded to 15 significant digits (this is 4.71238898038469) and expands that as octal digits as far as needed.<br />
<br />
This gives a periodically repeating number. The number of digits is also represented in octal, so instead of 200 digits it is actually 310 digits, finally giving:<br />
<pre><br />
4.5545743763144164456766617143366171162404440766665105335330776311513504520604364524762740226212061363100001776216741750712622557020442741544760057441760026766230424023460366047331305225241275347777145543054127636365666430221066167347236617261603127725745513663702031155234027041040155322217227723576660045156156</pre><br />
This number indeed does contain 666 four times (with one instance as 6666). It also contains 0000, 222, 444, and 7777, but they only appear once in a run.<br />
<br />
[http://en.wikipedia.org/wiki/Mathematical_coincidence Coincidentally], e+2 is also very similar to 1.5pi, although only to a few digits.<br />
<pre><br />
1.5π = 4.71238898038<br />
e+2 = 4.71828182846<br />
</pre><br />
<br />
The "Devil's Ratio" may be an allusion to the "[http://en.wikipedia.org/wiki/Tritone Devil's Interval]", aka the "Devil's Chord" or 'Diabolus in Musica' ('The Devil in music'), which is the name sometimes given to the harmony between a root note and its tritone/augmented fourth/diminished fifth. This note is situated halfway between octaves, and is named for its dissonant quality. It is possibly a cross-reference between this and the "[http://en.wikipedia.org/wiki/Golden_ratio Golden Ratio]".<br />
<br />
==Transcript==<br />
{{incomplete transcript}}<br />
:(π, 'Pi', crossed out) (1.5 π, 'Pau') (2 π, 'Tau', also crossed out)<br />
:A compromise solution to the Pi/Tau dispute<br />
{{comic discussion}}<br />
[[Category:Comics with color]]<br />
[[Category:Math]]</div>Psb777https://www.explainxkcd.com/wiki/index.php?title=1292:_Pi_vs._Tau&diff=530161292: Pi vs. Tau2013-11-18T13:35:40Z<p>Psb777: /* Explanation */</p>
<hr />
<div>{{comic<br />
| number = 1292<br />
| date = November 17, 2013<br />
| title = Pi vs. Tau<br />
| image = pi vs tau.png<br />
| titletext = Conveniently approximated as e+2, Pau is commonly known as the Devil's Ratio (because in the octal expansion, '666' appears four times in the first 200 digits while no other run of 3+ digits appears more than once.)<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete}}<br />
<br />
This is yet another of Randall's compromise comics. A few mathematicians argue as to whether to use pi, which is the ratio between a circle's diameter and its circumference, or tau, which is the ratio between a circle's radius and its circumference. Randall is suggesting using pau, which is a portmanteau between pi and tau, and is a number situated halfway between pi and tau. This number would be effectively useless, as there are currently no commonly used formulas that involve 1.5 pi or 0.75 tau.<br />
<br />
Some naively consider pi has having the "wrong" value because multiplying by the radius gives only half the circumference, they consider the 2 in (2 * pi * r) inconvenient. This ignores the convenience of the area being (pi * r^2). Also occasionally the argument is that the food, pi(e), is the whole thing, not half. Once again, when we eat pie it is not the crust we want, but the area! Note that the pi(e) justification for pi being half as big as it should be occurs only in English. And why cannot those who consider the conventions of maths wrong use (pi * D) for circumference. http://www.math.utah.edu/~palais/pi.html<br />
<br />
Anyway, the trivial nature of the argument is made plain in this comic! Were 'pau' used all the maths still works, proponents of 'tau' should do some real maths instead. Only the illiterate complain about "weird" spellings, similarly ... !<br />
<br />
<br />
The title text for the comic is also incorrect. The first 200 digits of 'pau' in octal are:<br />
<pre><br />
4.5545743763144164432362345144750501224254715730156503147633545270030431677126116550546747570313312523403514716576464333172731124310201076447270723624573721640220437652155065544220143116155742515634462<br />
</pre><br />
The sequence '666' does not occur at all. Both '2362' and '4376' occur twice, while both '362' and '431' occur three times. 39 other 3 digit sequences occur twice.<br />
<br />
The "Devil's Ratio" may be a cross-reference to the "Devil's Interval", aka tritone, augmented fourth, or diminished fifth. This note is situated halfway between octaves, and is named for its dissonant quality.<br />
<br />
==Transcript==<br />
{{incomplete transcript}}<br />
:(π, 'Pi', crossed out) (1.5 π, 'Pau') (2 π, 'Tau', also crossed out)<br />
:A compromise solution to the Pi/Tau dispute<br />
{{comic discussion}}<br />
[[Category:Comics with color]]<br />
[[Category:Math]]</div>Psb777https://www.explainxkcd.com/wiki/index.php?title=1292:_Pi_vs._Tau&diff=530151292: Pi vs. Tau2013-11-18T13:31:57Z<p>Psb777: /* Explanation */</p>
<hr />
<div>{{comic<br />
| number = 1292<br />
| date = November 17, 2013<br />
| title = Pi vs. Tau<br />
| image = pi vs tau.png<br />
| titletext = Conveniently approximated as e+2, Pau is commonly known as the Devil's Ratio (because in the octal expansion, '666' appears four times in the first 200 digits while no other run of 3+ digits appears more than once.)<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete}}<br />
<br />
This is yet another of Randall's compromise comics. A few mathematicians argue as to whether to use pi, which is the ratio between a circle's diameter and its circumference, or tau, which is the ratio between a circle's radius and its circumference. Randall is suggesting using pau, which is a portmanteau between pi and tau, and is a number situated halfway between pi and tau. This number would be effectively useless, as there are currently no commonly used formulas that involve 1.5 pi or 0.75 tau.<br />
<br />
Some naively consider pi has having the "wrong" value because multiplying by the radius gives only half the circumference, they consider the 2 in (2 * pi * r) inconvenient. This ignores the convenience of the area being (pi * r^2). Also occasionally the argument is that the food, pi(e), is the whole thing, not half. Once again, when we eat pie it is not the crust we want, but the area! Note that the pi(e) justification for pi being half as big as it should be occurs only in English. And why cannot those who consider the conventions of maths wrong use (pi * D) for circumference. http://www.math.utah.edu/~palais/pi.html<br />
<br />
Anyway, the debate is correctly trivialised in this comic!<br />
<br />
<br />
The title text for the comic is also incorrect. The first 200 digits of 'pau' in octal are:<br />
<pre><br />
4.5545743763144164432362345144750501224254715730156503147633545270030431677126116550546747570313312523403514716576464333172731124310201076447270723624573721640220437652155065544220143116155742515634462<br />
</pre><br />
The sequence '666' does not occur at all. Both '2362' and '4376' occur twice, while both '362' and '431' occur three times. 39 other 3 digit sequences occur twice.<br />
<br />
The "Devil's Ratio" may be a cross-reference to the "Devil's Interval", aka tritone, augmented fourth, or diminished fifth. This note is situated halfway between octaves, and is named for its dissonant quality.<br />
<br />
==Transcript==<br />
{{incomplete transcript}}<br />
:(π, 'Pi', crossed out) (1.5 π, 'Pau') (2 π, 'Tau', also crossed out)<br />
:A compromise solution to the Pi/Tau dispute<br />
{{comic discussion}}<br />
[[Category:Comics with color]]<br />
[[Category:Math]]</div>Psb777https://www.explainxkcd.com/wiki/index.php?title=1292:_Pi_vs._Tau&diff=530141292: Pi vs. Tau2013-11-18T13:21:50Z<p>Psb777: pizza pie</p>
<hr />
<div>{{comic<br />
| number = 1292<br />
| date = November 17, 2013<br />
| title = Pi vs. Tau<br />
| image = pi vs tau.png<br />
| titletext = Conveniently approximated as e+2, Pau is commonly known as the Devil's Ratio (because in the octal expansion, '666' appears four times in the first 200 digits while no other run of 3+ digits appears more than once.)<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete}}<br />
<br />
This is yet another of Randall's compromise comics. A few mathematicians argue as to whether to use pi, which is the ratio between a circle's diameter and its circumference, or tau, which is the ratio between a circle's radius and its circumference. Randall is suggesting using pau, which is a portmanteau between pi and tau, and is a number situated halfway between pi and tau. This number would be effectively useless, as there are currently no commonly used formulas that involve 1.5 pi or 0.75 tau.<br />
<br />
Some naively consider pi has having the "wrong" value because multiplying by the radius gives only half the circumference, they consider the 2 in (2 * pi * r) inconvenient. This ignores the convenience of the area being (pi * r^2). Also occasionally the argument is that the food, pi(e), is the whole thing, not half. Once again, when we eat pie it is not the crust we want, but the area! Note that the pi(e) justification for pi being half as big as it should be occurs only in English. And why cannot those who consider the conventions of maths wrong use (pi * D) for circumference. http://www.math.utah.edu/~palais/pi.html<br />
<br />
<br />
The title text for the comic is also incorrect. The first 200 digits of 'pau' in octal are:<br />
<pre><br />
4.5545743763144164432362345144750501224254715730156503147633545270030431677126116550546747570313312523403514716576464333172731124310201076447270723624573721640220437652155065544220143116155742515634462<br />
</pre><br />
The sequence '666' does not occur at all. Both '2362' and '4376' occur twice, while both '362' and '431' occur three times. 39 other 3 digit sequences occur twice.<br />
<br />
The "Devil's Ratio" may be a cross-reference to the "Devil's Interval", aka tritone, augmented fourth, or diminished fifth. This note is situated halfway between octaves, and is named for its dissonant quality.<br />
<br />
==Transcript==<br />
{{incomplete transcript}}<br />
:(π, 'Pi', crossed out) (1.5 π, 'Pau') (2 π, 'Tau', also crossed out)<br />
:A compromise solution to the Pi/Tau dispute<br />
{{comic discussion}}<br />
[[Category:Comics with color]]<br />
[[Category:Math]]</div>Psb777