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Science Forum

  1. 10 Apr '10 04:13
    This debate about whether e is a better number or pi is hilarious, especially the first debater. I'll only add the link to the first video, but I think all five parts are worth watching:

    http://www.youtube.com/watch?v=whpAX30vjoE&feature=related
  2. Standard member Agerg
    The 'edit'or
    04 May '10 19:16 / 2 edits
    Formula for pi:

    pi = 1+2-3+4+5-9+pi+10+11-21


    *edit* fixed
  3. Standard member adam warlock
    Baby Gauss
    04 May '10 19:53
    That series doesn't converge.
  4. Standard member Agerg
    The 'edit'or
    04 May '10 20:05 / 2 edits
    Originally posted by adam warlock
    That series doesn't converge.
    fair enough, wasn't actually trying to make a precise mathematical statement...just overly hastily highlighting one of the arguments that had me splitting my sides with laughter (and a + should have preceded the 5, not a - )
  5. Standard member adam warlock
    Baby Gauss
    04 May '10 20:12
    Originally posted by Agerg
    fair enough, wasn't actually trying to make a precise mathematical statement...just overly hastily highlighting one of the arguments that had me splitting my sides with laughter (and a + should have preceded the 5, not a - )
    I saw the humr in your post and replied with mock seriousness. But I forgot to put the smiley...
  6. 04 May '10 23:34
    I'm glad someone else enjoyed the debate
  7. Subscriber joe shmo
    Strange Egg
    05 May '10 01:04 / 1 edit
    Originally posted by Agerg
    Formula for pi:

    pi = 1+2-3+4+5-9+pi+10+11-21


    *edit* fixed
    the series still doesnt converge...correct?

    edit: nevermind, I thought that you were implying the corrected sign error effected the convergence.

  8. 05 May '10 08:49 / 2 edits
    Originally posted by joe shmo
    the series still doesnt converge...correct?
    I would say it has converged to pi.

    Definition: "A series S{a(n)} is said to 'converge' or to 'be convergent' when the sequence SN of partial sums has a finite limit."

    In this series, (S), it starts with 1+2-3+4+5-9+pi+10+11-21.
    It has only one value at a(1) (a very short series), which happens to be pi, which is finite.
    We can examine it by showing that sup(S) = inf(S) = pi, therefore S converges to pi.

    It converges alright.
  9. 05 May '10 16:12
    Originally posted by FabianFnas
    I would say it has converged to pi.

    Definition: "A series S{a(n)} is said to 'converge' or to 'be convergent' when the sequence SN of partial sums has a finite limit."

    In this series, (S), it starts with 1+2-3+4+5-9+pi+10+11-21.
    It has only one value at a(1) (a very short series), which happens to be pi, which is finite.
    We can examine it by showing that sup(S) = inf(S) = pi, therefore S converges to pi.

    It converges alright.
    The series does not converge! It bounces around rather wildly as its terms become more numerous.
  10. 05 May '10 16:36
    Originally posted by amolv06
    The series does not converge! It bounces around rather wildly as its terms become more numerous.
    Let's see if I can explain.

    (A): Do you think 3 + 5 is a series or a sum?
    (B): Do you think {3, 5} is a series or a sum?

    And (C): Do you think 1+2-3+4+5-9+pi+10+11-21 is a series or a sum?

    And what about pi itself, does that value diverge or converge?
  11. 05 May '10 17:37 / 1 edit
    Edited out
  12. 05 May '10 17:38 / 6 edits
    Let's see if I can explain.

    (A): Do you think 3 + 5 is a series or a sum?
    (B): Do you think {3, 5} is a series or a sum?

    And (C): Do you think 1+2-3+4+5-9+pi+10+11-21 is a series or a sum?

    And what about pi itself, does that value diverge or converge?


    A: Both
    B: Neither.
    C: Both

    Pi is a number. The term convergence is generally applied to an infinite series or sequence. I think the question, though semantically correct, is meaningless. I could be wrong about this, though.

    But this is largely irrelevant. We are asking whether the infinite series mentioned above converges. By your own definition this series does not converge. Your definition stated:

    "A series S{a(n)} is said to 'converge' or to 'be convergent' when the sequence SN of partial sums has a finite limit."

    No such finite limit exists for these partial sums. Or, if it does, as N approaches infinity, can you tell me this limit. Or can you prove that one exists? You can not.

    S1 = 1
    S2 = 3
    S3 = 0
    S4 = 4
    S5 = 9
    S6 = 0
    S7 = pi
    S8 = Pi+10
    S9 = pi + 21
    S10 = pi
    S11 = pi + 22
    S12 = pi + 45
    S13 = pi
    S14 = pi + 46
    S15 = pi + 93
    S16 = pi

    This sequence continues like this forever of course. As N approaches infinity there is no limit that the sequence of partial sums converges to. Hell, the sequence isn't even bounded. One of the conditions for convergence is that the sequence must be bounded.
  13. 05 May '10 18:08
    Originally posted by amolv06
    Let's see if I can explain.

    (A): Do you think 3 + 5 is a series or a sum?
    (B): Do you think {3, 5} is a series or a sum?

    And (C): Do you think 1+2-3+4+5-9+pi+10+11-21 is a series or a sum?

    And what about pi itself, does that value diverge or converge?


    A: Both
    B: Neither.
    C: Both

    Pi is a number. The term convergence is g ...[text shortened]... en bounded. One of the conditions for convergence is that the sequence must be bounded.
    I see only one item in that series and that is the expression 1+2-3+4+5-9+pi+10+11-21. Note there are no commas in between, nor semicolon. If you evaluate this you get pi. A value.

    So this is a finite series of only one term. S1 = pi. There is no S2, nor S3, etc. Only S1.

    What we discuss here is definitions and how we interprete the "1+2-3+4+5-9+pi+10+11-21". I know you know about series, and I think you know that I know some too. We can continue, but it doesn't lead to any meaningful discussion. So I stop here. You can have the last comment if you want.
  14. Subscriber joe shmo
    Strange Egg
    05 May '10 18:31
    Originally posted by FabianFnas
    I see only one item in that series and that is the expression 1+2-3+4+5-9+pi+10+11-21. Note there are no commas in between, nor semicolon. If you evaluate this you get pi. A value.

    So this is a finite series of only one term. S1 = pi. There is no S2, nor S3, etc. Only S1.

    What we discuss here is definitions and how we interprete the "1+2-3+4+5-9+pi+ ...[text shortened]... lead to any meaningful discussion. So I stop here. You can have the last comment if you want.
    just for clarification when I stated the series doesn't converge I thought of it in the way almov did, but because ( as fabian pointed out ) it is a series of only one term im going with fabian, if terms were separated by commas It doesn't converge.

    On a side note: It does leave me confused? Does the sum continue in a non-distinct way?
  15. Subscriber joe shmo
    Strange Egg
    06 May '10 04:18
    Originally posted by joe shmo
    just for clarification when I stated the series doesn't converge I thought of it in the way almov did, but because ( as fabian pointed out ) it is a series of only one term im going with fabian, if terms were separated by commas It doesn't converge.

    On a side note: It does leave me confused? Does the sum continue in a non-distinct way?
    and again sorry, I see the how the pattern is unique now.