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Does there exist a limit for calculating pi?

  1. Jul 28, 2010 #1
    note that by limit I mean the calculus operation, as in limf(x) as x->a.

    I was playing around with numbers earlier today and came up with a limit that gives an exact value for pi. I want to know if others have devised limits that equal to pi, because I am not sure if I am the first because my formula wasn't particularly complicated. If so, please post the formula. I apologize for not posting my limit here, but I hope you will understand why.
     
  2. jcsd
  3. Jul 28, 2010 #2

    mgb_phys

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    There are lots of series which calculate pi - given an infinite number of terms.
    You can't have an exact value of pi - except in the sense of an infinite series
     
  4. Aug 1, 2010 #3
    You most likely stumbled upon a derivation of one of the many infinite series that calculate out to Pi...

    There quite interesting in many cases.
     
  5. Aug 1, 2010 #4
  6. Aug 3, 2010 #5
    Pi is the number of times a diameter goes into its circles circumfrence... you can never have it perfectly accurate. I have a book which shows it to 10,000 digits. As I understant the most accurate super computer gives it to ~10,200. If you looked at a circle with radius 0.5 meters, the diameter would wrap around the circumfrence for 3 meters, 1 decimeter, 4 centimeters, 1 milimeter,... you can keep going and going and going. By deffinition its irrational, it seems like eventually you would get to a perfect spot where the diameter was exactly over the circumfrence without overlapping, alined atom by atom...
     
  7. Aug 3, 2010 #6

    mgb_phys

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    Not quite, the record is something like 3 trillion digits
     
  8. Aug 6, 2010 #7
  9. Aug 6, 2010 #8
    waste of a good computer & talent lol
     
  10. Aug 7, 2010 #9

    hotvette

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  11. Feb 22, 2012 #10
    I've found some limits for pi:
    -limit for x→0 (360/x*tan(x/2))
    -limit for x→∞ (x*sin(180/x))

    Just found them with simple geometry to divide the circle into multiple triangles. The first limit brings the arc of a triangle to 0, so it'll be very small. The second limit brings the number of triangles to ∞.

    Of course limits for pi exist, but as you can see, it's not possible to calculate it exactly. You can only approach the correct value, in this case by measuring/caculate the sin() or tan() of a very small arc.

    edit: i've used degrees.
     
    Last edited: Feb 22, 2012
  12. Feb 22, 2012 #11

    HallsofIvy

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    Here's an obvious sequence whose limit is [itex]\pi[/itex]:
    3, 3.1, 3.14, 3.141, 3.1415, 3.14159, 3.141592, ... !
     
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