pacomartin
pacomartin
  • Threads: 649
  • Posts: 7895
Joined: Jan 14, 2010
August 28th, 2014 at 11:21:06 PM permalink
Sometime after 1890, an Italian mathematician developed an 'averaging' method for the summation of divergent series.

He said there is a reasonable closed form answer for the S if S=-0+1-2+3-4+5-6+ ......

What is the value for S?
ThatDonGuy
ThatDonGuy
  • Threads: 123
  • Posts: 6748
Joined: Jun 22, 2011
August 29th, 2014 at 8:54:58 AM permalink
Well, Euler claimed it was
1/4


S = 1 - 2 + 3 - 4 + 5 - 6 + 7 - 8 + ...
= (1-2) + (3-4) + (5-6) + ...
= -(1 + 1 + 1 + 1 + ...)

3S = -(3 + 3 + 3 + 3 + ...)

S = ((1 - 4) + (2 - 5) + (3 - 6)) + ((7 - 10) + (8 - 11) + (9 - 12)) + ...
= -(3 + 3 + 3 + 3 + ...)
= 3S

Therefore, 2S = 0, so S = 0
DJTeddyBear
DJTeddyBear
  • Threads: 211
  • Posts: 11063
Joined: Nov 2, 2009
August 29th, 2014 at 9:31:49 AM permalink
Quote: ThatDonGuy

Well, Euler claimed it was

1/4

When adding and subtracting whole numbers, how is the result a fraction???
I invented a few casino games. Info: http://www.DaveMillerGaming.com/ ————————————————————————————————————— Superstitions are silly, childish, irrational rituals, born out of fear of the unknown. But how much does it cost to knock on wood? 😁
thecesspit
thecesspit
  • Threads: 53
  • Posts: 5936
Joined: Apr 19, 2010
August 29th, 2014 at 9:45:37 AM permalink
https://www.youtube.com/watch?v=w-I6XTVZXww

You have to accept 1-1+1-1+1.... sums to 1/2.
"Then you can admire the real gambler, who has neither eaten, slept, thought nor lived, he has so smarted under the scourge of his martingale, so suffered on the rack of his desire for a coup at trente-et-quarante" - Honore de Balzac, 1829
DJTeddyBear
DJTeddyBear
  • Threads: 211
  • Posts: 11063
Joined: Nov 2, 2009
August 29th, 2014 at 11:58:11 AM permalink
Quote: thecesspit

You have to accept 1-1+1-1+1.... sums to 1/2.

I didn't watch the video yet, but your new spoiler?
1/2?
That's the average of any two consecutive sums. Although I agree the answer is either 1 or 0, to average them is wrong.

That said, here's
S = Negative infinity.
Which allows S = 3S
I invented a few casino games. Info: http://www.DaveMillerGaming.com/ ————————————————————————————————————— Superstitions are silly, childish, irrational rituals, born out of fear of the unknown. But how much does it cost to knock on wood? 😁
thecesspit
thecesspit
  • Threads: 53
  • Posts: 5936
Joined: Apr 19, 2010
August 29th, 2014 at 12:48:29 PM permalink
There's a bunch of similar videos from Numberphile on the subject, and it goes into the Riemann Zeta function quite well.

The -1/12 answer has been used in physics quite nicely. Even tough it blows my mind.
"Then you can admire the real gambler, who has neither eaten, slept, thought nor lived, he has so smarted under the scourge of his martingale, so suffered on the rack of his desire for a coup at trente-et-quarante" - Honore de Balzac, 1829
  • Jump to: