1. Standard memberadam warlock
    Baby Gauss
    Ceres
    Joined
    14 Oct '06
    Moves
    18375
    21 Aug '11 10:49
    Where's the mistake?

    http://memebase.com/2010/11/30/memes-troll-math-pi/?fb_ref=sharetestE_v3
  2. Standard memberPalynka
    Upward Spiral
    Halfway
    Joined
    02 Aug '04
    Moves
    8702
    21 Aug '11 13:121 edit
    The length of the perimeter at the limit is not necessarily the limit of the approaching perimeters.

    People hated on me when I argued something like this during the "balls in a bag" thread.
  3. Standard memberadam warlock
    Baby Gauss
    Ceres
    Joined
    14 Oct '06
    Moves
    18375
    21 Aug '11 19:09
    Originally posted by Palynka
    The length of the perimeter at the limit is not necessarily the limit of the approaching perimeters.

    People hated on me when I argued something like this during the "balls in a bag" thread.
    Yes I also guess that that is the case even though I don't have a rigorous proof of that.

    Another mistake is that this shows that Pi=2 and not Pi=4 as claimed.
  4. Cape Town
    Joined
    14 Apr '05
    Moves
    52945
    21 Aug '11 19:41
    Originally posted by adam warlock
    Yes I also guess that that is the case even though I don't have a rigorous proof of that.
    It should be trivial to give a proof, if a similar attempt is made to show that the length of the line y=x from the origin to (1,1) is 2 units.
    The line is divided into two and two right angled triangles are drawn, and the process is iterated. It can be shown that for any given iteration, the line y=x remains sqrt(2) units and the length of the horizontal and vertical line segments remain 2.
  5. Standard memberPalynka
    Upward Spiral
    Halfway
    Joined
    02 Aug '04
    Moves
    8702
    21 Aug '11 22:17
    Originally posted by adam warlock
    Another mistake is that this shows that Pi=2 and not Pi=4 as claimed.
    Why do you say that?
  6. Standard memberadam warlock
    Baby Gauss
    Ceres
    Joined
    14 Oct '06
    Moves
    18375
    21 Aug '11 22:46
    Originally posted by Palynka
    Why do you say that?
    Because for some strange reason I got r=1 instead of D=1 in my head.

    Move along, nothing to see here...

    😞😞😞😞
  7. Cape Town
    Joined
    14 Apr '05
    Moves
    52945
    22 Aug '11 11:37
    Can anyone devise a fractal line which appears to approximate a circle, yet whose length is infinite? (thus supposedly proving pi to be infinite)
  8. Germany
    Joined
    27 Oct '08
    Moves
    3081
    22 Aug '11 12:43
    Originally posted by Palynka
    The length of the perimeter at the limit is not necessarily the limit of the approaching perimeters.

    People hated on me when I argued something like this during the "balls in a bag" thread.
    The length of the perimiter in the limit is 4, but the curvature at some point on the circle is not the same as it would be for a circle (at a given point the line is either horizontal or vertical), i.e. the limiting shape is not a circle, it just looks like one.
  9. Standard memberPalynka
    Upward Spiral
    Halfway
    Joined
    02 Aug '04
    Moves
    8702
    22 Aug '11 13:142 edits
    Originally posted by KazetNagorra
    The length of the perimiter in the limit is 4, but the curvature at some point on the circle is not the same as it would be for a circle (at a given point the line is either horizontal or vertical), i.e. the limiting shape is not a circle, it just looks like one.
    What do you mean by "in the limit"? And "it just looks like a circle"? Seems to me you're talking out of your backside.

    The sequence converges to a circle indeed. Take any point of the circle, the sequence will approximate to it in the limit (some points it converges to in finite iterations, the rest in infinite ones) and it will converge to no point outside of the circle.
  10. Standard memberPalynka
    Upward Spiral
    Halfway
    Joined
    02 Aug '04
    Moves
    8702
    22 Aug '11 13:18
    http://www.mathpages.com/home/kmath063.htm
  11. Germany
    Joined
    27 Oct '08
    Moves
    3081
    22 Aug '11 13:29
    Originally posted by Palynka
    What do you mean by "in the limit"? And "it just looks like a circle"? Seems to me you're talking out of your backside.

    The sequence converges to a circle indeed. Take any point of the circle, the sequence will approximate to it in the limit (some points it converges to in finite iterations, the rest in infinite ones) and it will converge to no point outside of the circle.
    Like your link in your next post says - not all properties converge to it "being a circle". Yes, every point on the "jagged" circle corresponds to a point on a "real" circle, but the curvature and circumference are different, so it's not a "real" circle. The infinitely-sided "jagged" circle will have a circumference 4, not pi.
  12. Standard memberPalynka
    Upward Spiral
    Halfway
    Joined
    02 Aug '04
    Moves
    8702
    22 Aug '11 13:35
    Originally posted by KazetNagorra
    Like your link in your next post says - not all properties converge to it "being a circle". Yes, every point on the "jagged" circle corresponds to a point on a "real" circle, but the curvature and circumference are different, so it's not a "real" circle. The infinitely-sided "jagged" circle will have a circumference 4, not pi.
    Wrong again, not all properties need to converge, there can be (and there is) discontinuity in some. In this case, the perimeter of the shape remains 4 but at the limit there is a discontinuity.

    Which point of the circle does it not converge to?
    Which points outside of the circle does it converge to?

    If your answers to these two questions are both "none", then clearly it converges to the circle.
  13. Germany
    Joined
    27 Oct '08
    Moves
    3081
    22 Aug '11 13:58
    Originally posted by Palynka
    Wrong again, not all properties need to converge, there can be (and there is) discontinuity in some. In this case, the perimeter of the shape remains 4 but at the limit there is a discontinuity.

    Which point of the circle does it not converge to?
    Which points outside of the circle does it converge to?

    If your answers to these two questions are both "none", then clearly it converges to the circle.
    Yes, like I said all points converge to points on a circle with d = 1, but the final shape is not a circle because the definition of a circle entails more than the location of its points.
  14. Standard memberPalynka
    Upward Spiral
    Halfway
    Joined
    02 Aug '04
    Moves
    8702
    22 Aug '11 14:071 edit
    Originally posted by KazetNagorra
    the definition of a circle entails more than the location of its points.
    If all the points are at the exact same location, what properties are different?
  15. Cape Town
    Joined
    14 Apr '05
    Moves
    52945
    22 Aug '11 14:41
    Originally posted by Palynka
    If all the points are at the exact same location, what properties are different?
    The points can never be in the exact same location as in the circle, one point can never be vertically above another (in the arc above the x-axis) whereas in the jagged shape for any given point on the circle there is always another point not on the circle vertically above it. There are always point not on the circle.
Back to Top