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Math Idle

Happy Tau Day 298

Forget about Pi Day, today we celebrate something twice as good: Tau Day. For far too long, Pi has been the bride and Tau has been the bridesmaid. As Michael Hartl points out in The Tau Manifesto, "Pi is a confusing and unnatural choice for the circle constant." He is giving a talk at the California Institute of Technology based on the Manifesto, with pie served at the end. "Twice as many as you might expect," he says.

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Happy Tau Day

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  • As Weebl and Bob might say...

  • by elrous0 ( 869638 ) * on Tuesday June 28, 2011 @11:00AM (#36597492)

    It's 4*Pi, which makes it TWICE as kick-ass as Tau!

    • Ah, you went the other direction with that. I invented "Pie day." It has less to do with numbers or greek letters and more to do with pastry and delicious.
  • I guess I will have to go down to Bakers Square and get 2 pies today.
  • by Maximum Prophet ( 716608 ) on Tuesday June 28, 2011 @11:06AM (#36597558)
    Back in 7th grade the teacher wanted us to show our work. Most of the time I could figure out the stuff in my head, so I didn't want to do that. In order to freak out the teacher, I memorized the multiplication table of (single digit) * 3.14

    After that I could write stuff like 67*pi = 188.40 + 21.98 = 210.38 (vertically)

    The teacher never commented on showing my work after that...
    • by geekoid ( 135745 ) <> on Tuesday June 28, 2011 @11:39AM (#36598004) Homepage Journal

      Then you teacher failed. Showing your work is about knowing the procedure to do something.

      Even the dimmest child can look at: 4 * X = 8 and KNOW X=2. But the real lesson is showing the work so when it's not that easy you can get a correct answer.
      You use an easy example so when they finish going through the correct steps they can know they did it correctly.

      • One of the worst things you can do to a student that truly understands the material is to drag them down and force them to do what they consider menial tasks. It is a fine line, because I agree that it is important that students learn how to work through more complicated problems. However, when someone has already demonstrated their ability and is effectively doing homework and writing tests simply to "jump through the hoops", you can seriously cripple their interest in pursuing the field entirely and drive

        • by AikonMGB ( 1013995 ) on Tuesday June 28, 2011 @12:03PM (#36598412) Homepage

          Now for the anecdote part relating how a "one-size-fits-all" education scheme doesn't work in practice:

          In elementary school, my brother's teacher would give the class spelling quizzes. He scored 100% on the first quiz. The second quiz rolled around and he scored 100% again. He was distraught because many of his colleagues had gotten stickers on their returned quizzes as rewards, and yet he had gotten nothing. The teacher's explanation was that the rewards were for improvement on the quizzes -- if you did better than last time, you got a sticker.

          His response was to intentionally fail the subsequent quiz, and then slowly build up his score to 100%, and then restart the process. The teacher was concerned about his inconsistent spelling skills and thought he might have problems with distraction; my parents understood what had happened immediately.

          When you reduce education to the lowest common denominator, you remove any chance for the gifted, the skilled, the interested, and the excited students to excel at their studies.


          • And my teacher taught my that "seperate" is a verb, while "separate" is an adjective. She also taught the hard-and-fast "i before e" rule and caused me to lose a spelling bee, ironically by misspelling "forfeit".

            I'll believe pretty much any crazy story you tell me about dumb ways of teaching spelling.

        • by Roger W Moore ( 538166 ) on Tuesday June 28, 2011 @12:22PM (#36598772) Journal

          One of the worst things you can do to a student that truly understands the material is to drag them down and force them to do what they consider menial tasks.

          Exactly. What the teacher should have done is give them a question that they cannot do in their heads. If they can do 67pi then how about 67e or 123*sqrt(3) etc. That does not drag them down but does teach them that, smart as they are, there are always more difficult problems out there so they should not get too cocky.

        • Showing your work to me was never a benefit for me. Grading homework, I actually much preferred the people who just put down the answer. Is it right? Full points. Is it wrong? Zero points. I could whip through a 20 part homework in about 30 seconds flat. When they showed their work, I actually had to follow through and check for mistakes. It was 100% upside for the students: if they made a boneheaded mistake (64 bitshifted twice to the right = 256), they got nearly full points. Showing your work meant that

      • But the real lesson is showing the work so when it's not that easy you can get a correct answer.

        So it has become a problem of input devices. I think divide by 4 on each side, but how do I write this down as quickly as I think it?

    • Your not special.
    • by jfengel ( 409917 )

      Then your teacher failed at teaching you about significant figures. 67*pi=210.49, not 210.38. The difference is small, but you were only working with 3 significant figures of pi, so everything past the decimal point is going to be random. It just so happens that the next decimal places are small (.00159), which helps on the next digit, but the final digit is pretty much entirely junk.

      210 is good enough for most purposes, for the same reason that 3.14 is good enough for most purposes, and the teacher shou

  • Angles: 2Pi in a full circle? Somehow it's more satisfying if the proportion of a circle were between 0 and 1: xTau. So half a circle would be (1/2)Tau, not the whole-looking 1Pi.

    If you look at various "important" equations, you often end up seeing 2Pi in there. Gaussian, Riemann, Fourier. Another one: h/2Pi, h being Planck's constant. Why not make 2Pi the constant?

    Even Pi*r^2 is more appropriate as (Tau/2)r^2, if you compare with (1/2)mv^2.

    I have to admit I was not violently emotional when I read the argum

    • I think it's a false dichotomy to say you have to have one or the other.

      Yes, calculating circles, cosines, etc, with Tau is going to be way easier than using 2Pi, but, for most non-math types, I can't imagine them needing that kind of distinction.

      Plus additional greek letters always look cool.

    • by Twinbee ( 767046 )

      And why not scrap even Tau and have just 0-1 for a full circle? Yes I know the advantages of radians, but I've always found it useful to use cycles/revolutions for any trigonometric work. I'm amazed that it's not in more common use. With calculators, you get radians and degrees, but never cycles.

  • Tau is already super overloaded. In grad school, we always wrote "2pi" as k_k, that is, k with a subscript k (it doesn't look as weird in handwriting, because the subscript).

    Of course, it's pronounced "cake".
    • Why on earth did you do this? I've never heard of this notation.
      • You have never heard of this notation because we invented it. We wanted/needed a better way to express 2pi because, as TFA states, pi is a stupid choice for a constant and when you are doing physics you end up writing 2pi constantly; having a constant for 2pi leads to more intuitive notation that helps to clarify relationships that are less obvious when you have stray factors of two which by rights ought to belong to their pi instead getting loose and wandering about your analysis.

        There seems to be some mom
        • Also, 2pi takes 3 characters, tau takes 3 characters, while .5tau takes 5, 1/2tau and 0.5tau take 6, (1/2)tau 8.

          • by blueg3 ( 192743 )

            If you're writing out "2pi" and "(1/2)tau", you're doing it wrong.

            2 pi either takes two characters, one of which is Greek, or four: 2 \pi.

    • And of course 3pi was k_k_k... wait...
  • Wait, it's not the 62nd of August yet... insensitive clod!

  • "... Yer a Tau!"

  • Tau is already used to describe the relationship of speed to the apparent speed of the passage of time. Also, both Pi and "Tau" are irrational, and since Tau is 2pi, this seems like a huge fucking waste of nerd time.
    • The point of Tau is not to please nerds or mathematicians.

      Although I would love to see mathematicians change their ways, I’m not particularly worried about them; they can take care of themselves. It is the neophytes I am most worried about, for they take the brunt of the damage

    • Tau is already used to describe the relationship of speed to the apparent speed of the passage of time.

      And pi is already used to describe conjugate momentum, as Tau Manifesto [] explains. Wikipedia lists a whole bunch of other meanings of pi [].

  • I might agree that it makes sense to switch from pi to tau after I agree it makes sense to change from imperial measurement to the metric system.

    Note that at this time I do not agree that it makes sense to switch to metric, so we may be in for a bit of a wait...

    • Luckily, you can easily write T=2Pi in your equations. No need to reprint thousands of T-Shirts.

      I think the main point of the rant is that Tau somehow seems more fundamental. What defines a circle? A locus of points on a plane equidistant from a certain point. That distance is somehow more fundamental than 2r, even if the distinction is trivial.

    • by geekoid ( 135745 )

      What possible reason could you have not to finish switching to metric?

      • Because outside of the world of digital calculators metric sucks?

        We can have a quarter pounder with cheese. You have the Royale with cheese. One tells you how much you are actually getting. Otherwise you've got to rattle off "I want a 113.398093g with cheese".

        • by geekoid ( 135745 )

          So labels confuse you?

          By your reasons the 'Big Mac' doesn't make sense and no one could possible know how much meat is there. In fact, how many burgers are known by there weight? A very few, overall.

          It is far easier to teach kids metric then imperial. They get it faster, it makes sense. Kids like there to be a graspable reason for doing things. Metric has that.

          It's also become incredible more expensive and difficult to work outside the US without using metric.
          That said, if the US official went metric, that

          • Aren't England's road signs in miles as well (and weight still given as stones by the populace)? Great example of metric adoption there.

        • But I'm sure Americans are gonna love the Quarter-Kilo with Cheese. More than double the beef of the Quarter Pounder!

          • by treeves ( 963993 )

            No, McDonalds would have to go to the 1 Hectogram with Cheese for economic reasons (and it'd make dietary sense too), and they'll lose just a little meat. "Hectogram" just sounds so scientific and mathematical and not so tasty.

  • by CmdrPorno ( 115048 ) on Tuesday June 28, 2011 @11:30AM (#36597872)

    (Which apparently triggers the lameness filter...)


    Why does the lameness filter think Billy Mays is lame?

  • And if he didn't know that, then he should get back to the books and stop wasting time.

    • Pi is used for things other than the circle constant, too...

      • by geekoid ( 135745 )

        See, this is what I get for not taking my own advise and using a tilde.

        And if he didn't know that, then he should get back to the books and stop wasting time~

        now it's funny.

    • by blueg3 ( 192743 )

      All of the Greek and Latin characters are used for more than one thing just in physics alone -- to say nothing of subscripts, typographical variants like blackletter, decorator symbols, and the occasional Hebrew letter.

  • Tau for uber math nerds, physicists, EE geeks and anyone else who needs to calculate an arc tangent and Pi for everyone who just needs to figure out what diameter pipe they need to fix their sink?

    • You mean kinda how we screw up elementary and middle school students with a different set of symbols for the multiplication and division operators? Sure why not, lets add more stumbling blocks.
    • Pi is better for uber math nerds, physicists and EE geeks because there are lots of circumstances where you deal with the integer multiples of Pi, including odd multiples. The only people who like 'tau' are the math/science groupies online who worship, not practice, and think that Fermat's Last Theorem was an important problem.

  • That is quite possibly the most beautiful song I've ever heard.
    • by Twinbee ( 767046 )

      I hope you're joking. The instruments make it sound better than it really is.

      You do realize you'd get similar crap with random numbers.

  • Celebrate a day based on 2*pi? No thanks. However, I will celebrate 2.556*pi day. I will likely even have cake on that day. It's the day that I turn approximately 11.46*pi years old.

Never worry about theory as long as the machinery does what it's supposed to do. -- R. A. Heinlein