20201120, 07:01  #34 
Einyen
Dec 2003
Denmark
2^{6}×7^{2} Posts 

20201203, 15:52  #35 
Feb 2016
UK
419 Posts 
Only just saw this, forgot this forum was here. Ycruncher would love as much ram as is needed, but in reality no consumer attainable system can possibly have enough ram for the bigger runs. We're talking well into the TB that not even high end servers can reach. And that's putting aside the cost of that much ram even if you could put it in a single system. So the practicality of it is, you have to use some form of swap as a less insane cost substitute, and that is where the optimisation needs to go.

20201203, 15:57  #36 
"Mike"
Aug 2002
3·7·389 Posts 
To prove that you computed x digits of pi, couldn't you store only a checksum of all of the digits and keep the last digit "for fun"?

20201203, 16:32  #37 
Bamboozled!
"πΊππ·π·π"
May 2003
Down not across
2×3×13×137 Posts 

20201205, 14:28  #38 
"Mike"
Aug 2002
3·7·389 Posts 

20201205, 16:58  #39 
6809 > 6502
"""""""""""""""""""
Aug 2003
101Γ103 Posts
22561_{8} Posts 
The last 10 digits and a 128 bit checksum would be enough, I would suppose.

20201205, 17:10  #40 
Undefined
"The unspeakable one"
Jun 2006
My evil lair
6,143 Posts 
Digit extraction algorithms exist. So merely producing a few trailing digits wouldn't be enough to prove you computed all the digits up to that point.
A hash of all digits up to your claimed last digit would be suitable IMO. 
20201205, 18:08  #41  
"Robert Gerbicz"
Oct 2005
Hungary
2^{2}·367 Posts 
Quote:
Quote:
But even giving only the last few bits would enable to provide a fake proof, just give the exact bits from BBP and give a trash hash value. [notice that even giving say hundred consecutive bits of Pi is "easy"]. Much better: if you're claiming a world record then I would choose 1 million random positions and you should give the bits for each of these positions. The check: select say 2025 positions and verify the bits with BBP. You have an extremely small probability to fake me. This is assuming that when you need multiple bits of Pi then there is no faster method than to use the BBP formula for each position. 

20201207, 07:41  #42 
Romulan Interpreter
Jun 2011
Thailand
2^{2}·17·139 Posts 
Group the bytes by 32 or 64 and compute a SHA256 or SHA512 of it. I don't believe anybody would contest that.

20201207, 14:05  #43  
"Robert Gerbicz"
Oct 2005
Hungary
2^{2}×367 Posts 
Quote:
Code:
a19a6c3a75783b6b5deee64777873ae207764837e769eedbe9b4c485d94b2986 Last fiddled with by R. Gerbicz on 20201207 at 14:05 Reason: typo 

20201208, 07:01  #44 
Romulan Interpreter
Jun 2011
Thailand
2^{2}·17·139 Posts 
Yep. After I remake the calculus to see if I get the same value...
I assume somebody verifies this things, anyhow... Or not? Last fiddled with by LaurV on 20201208 at 07:03 
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