The Pi Manifesto

1. This is a good discussion to have. Those who are dismissive show, in my opinion, a lack of intellectual curiosity. Elegance for the sake of elegance is a worthwhile goal.<p>2. From a pragmatist point of view, you're right, it doesn't matter. You continue reading and writing PHP and using π. They both get the job done. You don't have to participate any further.<p>3. There will be 2s floating around some equations forever, whether using π or τ. That's not the point. The point is not "cleanliness" or even teaching efficacy. The point is elegance and that comes from <i>meaning</i>. What does the equation <i>say?</i> Equation cleanliness and ease of understanding are both worthwhile side effects, but it's <i>meaning</i> that's important.<p>4. Going from π to τ would be nontrivial, and would involve confusion of its own. That makes it not worth it to some people, and that's a valid opinion.<p>5. This article suffers from more selection bias than the Tau Manifesto. The radius is the undisputed king of the circle; it defines it. The area of a circle is not, after all, π * (D/2)^2. But it's not about prettiness, it's about <i>meaning</i>! Area is a property <i>defined by the integral</i>, which has a natural meaning and result with τ. The result may be a little equation that's pretty or not depending on your point of view, but it's just a shortcut.<p>6. The other examples in the article similarly fall apart when <i>meaning</i> is considered.

I just want to ask all of the Pi/apathetic people-- how long did it take you to understand radians? For me, it was a week before I was comfortable naming any angle in radians in a reasonable amount of time (this is after a week of drilling).<p>This is just my point of view, but calculating radians was a <i>significant</i> roadblock into making quick trigonometric calculations. In fact, I'd have to say it was the biggest roadblock. This has nothing to do with how "clean" it looks or how I "feel" about how it's presented.<p>That said, I don't think it's worth it to make the switch because of all the hassle. I'm just curious about all of the hostility towards Tauists.<p>tldr; it has nothing to do with any mathematical formula looking "cleaner," but everything to do with teaching math effectively.

Damnit, this is just as bad as the tau manifesto. The point is that it doesn't matter what the bloody constant is, we don't need any -more- goddamn manifestos. Call it an arc constant or an angle constant or whatever you want.<p>However, there is one massive abuse of terminology that is driving me insane, which is the use of the phrase "Quadratic forms". E = 1/2 k x^2 is not a quadratic form. A quadratic form is a homogeneous polynomial of degree two, and it's a topic discussed in number theory:<p><a href="http://en.wikipedia.org/wiki/Quadratic_form" rel="nofollow">http://en.wikipedia.org/wiki/Quadratic_form</a><p>The vast majority of people will never encounter a legitimate <i>quadratic form</i>. Call it a quadratic equation or whatever -- it's not a quadratic form. Both the tau manifesto and the pi manifesto got this bit manifestly <i>wrong</i>.

I disagree with change for change's sake. This whole tau thing is born of some idealist that thinks things only make sense his/her own way.<p>The only thing I didn't see in the article is that the symbol visually looks like a T, so when you see it in a formula, you have to really look at it to know what's going on.

The practical problem with tau is, as was pointed out in the article, tau is already used for other things. Shear stress, torque, time constants, you name it.<p>pi is a notational freak in that it represents something so fundamental that few dare tread upon the usage---pi truly is a globally reserved name. To a lesser extent, the same is true of e, but even a number as important as i doesn't enjoy this property: electrical engineers use j for sqrt(-1) because i is current.<p>So let's say we all start using tau. Then I decide I'm going to do some basic rotational mechanics, and now I have two taus, one for torque and one for 2pi. OK, that's a no-go. How about we just redefine pi=2pi? Well... how do we know whether someone means pi=~6.28, or pi=~3.14?<p>It's just no good. Tau is not a viable candidate name for the constant equal to 2pi. Find another character in another language. How about Pei (Hebrew)?

Here is what is wrong with the "anti-tauist" rants:<p>They take a bunch of people who already learned the subject and presume that those people are experts a teaching said subject. These people always assume that the way they learned is best, because "dammit, it was good enough for me". They just can't see any other way.<p>Sadly, this ignores all of the other people, who may be capable of understanding and properly using the subject if presented in a different way.<p>For pedagogical purposes, Tau is worth a shot, if it helps some people get to the point that they realize "for the math the constant doesn't matter".<p>Just like anything else: try to teach broadly, and let the experts do the adjusting, not make the novice bend to the expert's will or be damned.

I stopped reading early, when he's claiming pi is better for the area of a circle, because that revealed that the author hasn't really thought about this very much.<p>If you look at the equations for the volumes of spheres in n dimensions (with 2D being just one of them), tau shows a clean pattern. pi leaves you with a mess.

When you ask hard-core Tauists what the area of a unit circle is, do they actually answer "tau over two"? Or do they just say "pi"?<p>By the way, this whole discussion reminds me of what W.V.O. Quine called "mathematosis".

I've considered refactoring my pathfinding code - 2.0 is this magic constant that is floating around all over my code.<p>Inertia has prevented me.

All this will ever lead to is Indiana passing a new law that Tau is exactly 6.<p><a href="https://secure.wikimedia.org/wikipedia/en/wiki/Indiana_Pi_Bill" rel="nofollow">https://secure.wikimedia.org/wikipedia/en/wiki/Indiana_Pi_Bi...</a>

For me this debate is the monumental evidence that when people get obsessed over something their intellectual openness shrinks to a very small dividend of pi, sorry I meant tau :)

TLDR:<p>- The area of a unit circle is Pi.<p>- The Tau Manifesto is full of selective bias. They pinpoint formulas that contain 2π while ignoring other formulas that do not.

eagerly awaiting π vs τ rap wars..

And I open my eggs on the little end...

Given the nature of the debate, I think it's funny that the HN URL here ends in "404".

Is the authors replacement of "Tauists" with "Taoists" and "Tau" with "Tao" an indication that he is repressing his subconscious belief that Tau is the way?