4 ms·

William Jones, the Welshman who invented π

32 points by akashtndn 12y ago

amelius 12y ago
But he made a big mistake [1] [1] http://www.math.utah.edu/~palais/pi.html http://www.math.utah.edu/~palais/pi.html
- wyager 12y ago
  You're getting downvoted pretty hard, but I generally agree. Using tau (2π) feels much more natural. It seems like, in physics, 90% of the time we use π, it shows up with a 2 next to it. And the article you linked has a good point; if we called τ a "turn", statements about getting arc lengths from angles and radii would translate to natural language much better. τ not only corresponds to full rotations, but also to full periods of sine and cosine functions.
mjklin 12y ago
Why would the British have Pi day when they write the date 14/3?
- darklajid 12y ago
  Because we don't have 14 month and otherwise they would never be able to celebrate this glorious occasion. (Really, the month/day format is stupid, but for novelty purposes that shouldn't matter?)
  - fennecfoxen 12y ago
    Why is month/day stupid? What other formats do we use in daily life where the least significant digit comes first? No, what's stupid is month/day/year. ;)
  - iand 12y ago
    31 April is British Pi day
- ojbyrne 12y ago
  Because they sometimes (and apparently historically) write 3/14: https://en.wikipedia.org/wiki/Date_format_by_country https://en.wikipedia.org/wiki/Date_format_by_country
  - iand 12y ago
    No, it's never written as numbers that way. But writing March 3, 2014 is fairly common.
- david-given 12y ago
  The next proper Pi Day is in a bit over a thousand years, on 3141-5-9. Of course, if you think that's a bit long to wait for, the one after that is 28000 years afterwards, on 31415-9-6. I'm looking forward to it!
cnvogel 12y ago
Typography-Remark: The font used at ycombinator (Verdana) makes the title almost useless, as "π" its shown as a bottom-open-rectangle. There's a special codepoint for the mathematical alphanumeric italic symbol 𝜋 (Unicode 0x1D70B)... https://en.wikipedia.org/wiki/Mathematical_operators_and_symbols_in_Unicode#Mathematical_Alphanumeric_Symbols_block https://en.wikipedia.org/wiki/Mathematical_operators_and_sym...
- wanderingstan 12y ago
  This symbol does not display for iOS. (Sadly lots of Unicode mathematical symbols are missing from iOS, which is why those hacks for showing text in Fraktur or italics don't work either.)

32 points by akashtndn 12y ago

amelius 12y ago

But he made a big mistake [1] [1] http://www.math.utah.edu/~palais/pi.html http://www.math.utah.edu/~palais/pi.html

wyager 12y ago
You're getting downvoted pretty hard, but I generally agree. Using tau (2π) feels much more natural. It seems like, in physics, 90% of the time we use π, it shows up with a 2 next to it. And the article you linked has a good point; if we called τ a "turn", statements about getting arc lengths from angles and radii would translate to natural language much better. τ not only corresponds to full rotations, but also to full periods of sine and cosine functions.

mjklin 12y ago

Why would the British have Pi day when they write the date 14/3?

darklajid 12y ago
Because we don't have 14 month and otherwise they would never be able to celebrate this glorious occasion. (Really, the month/day format is stupid, but for novelty purposes that shouldn't matter?)
- fennecfoxen 12y ago
  Why is month/day stupid? What other formats do we use in daily life where the least significant digit comes first? No, what's stupid is month/day/year. ;)
- iand 12y ago
  31 April is British Pi day
ojbyrne 12y ago
Because they sometimes (and apparently historically) write 3/14: https://en.wikipedia.org/wiki/Date_format_by_country https://en.wikipedia.org/wiki/Date_format_by_country
- iand 12y ago
  No, it's never written as numbers that way. But writing March 3, 2014 is fairly common.
david-given 12y ago
The next proper Pi Day is in a bit over a thousand years, on 3141-5-9. Of course, if you think that's a bit long to wait for, the one after that is 28000 years afterwards, on 31415-9-6. I'm looking forward to it!

cnvogel 12y ago

Typography-Remark: The font used at ycombinator (Verdana) makes the title almost useless, as "π" its shown as a bottom-open-rectangle. There's a special codepoint for the mathematical alphanumeric italic symbol 𝜋 (Unicode 0x1D70B)... https://en.wikipedia.org/wiki/Mathematical_operators_and_symbols_in_Unicode#Mathematical_Alphanumeric_Symbols_block https://en.wikipedia.org/wiki/Mathematical_operators_and_sym...

wanderingstan 12y ago
This symbol does not display for iOS. (Sadly lots of Unicode mathematical symbols are missing from iOS, which is why those hacks for showing text in Fraktur or italics don't work either.)