Bitcoin Forum
December 08, 2016, 06:25:45 AM *
News: To be able to use the next phase of the beta forum software, please ensure that your email address is correct/functional.
 
   Home   Help Search Donate Login Register  
Pages: [1]
  Print  
Author Topic: Measurement of Difficulty  (Read 1483 times)
worldinacoin
Hero Member
*****
Offline Offline

Activity: 658



View Profile WWW
April 11, 2012, 04:41:45 AM
 #1

How do I measure difficulty?  For eg I see Difficulty   1626553 , what does 1626553 means?  How many ghash does it translate to?
1481178345
Hero Member
*
Offline Offline

Posts: 1481178345

View Profile Personal Message (Offline)

Ignore
1481178345
Reply with quote  #2

1481178345
Report to moderator
1481178345
Hero Member
*
Offline Offline

Posts: 1481178345

View Profile Personal Message (Offline)

Ignore
1481178345
Reply with quote  #2

1481178345
Report to moderator
Advertised sites are not endorsed by the Bitcoin Forum. They may be unsafe, untrustworthy, or illegal in your jurisdiction. Advertise here.
1481178345
Hero Member
*
Offline Offline

Posts: 1481178345

View Profile Personal Message (Offline)

Ignore
1481178345
Reply with quote  #2

1481178345
Report to moderator
Foxpup
Legendary
*
Offline Offline

Activity: 1708



View Profile
April 11, 2012, 05:10:42 AM
 #2

Difficulty is the maximum possible hash target divided by the current hash target. The average time to find a block (in seconds) is equal to the current difficulty times 2^32 (4,294,967,296) divided by your hashrate (in hashes per second) (eg, if your hashrate is 1 Ghash/s = 1,000,000,000 hashes per second then the average time it will take you to find a block is (1,626,553 x 4,294,967,296 / 1,000,000,000 = 6,985,992 seconds = 80 days).

Since the difficulty is adjusted so that miners find blocks on average once every 10 minutes (600 seconds), the total hashpower of the network is equal to the difficulty times 2^32 divided by 600 (eg, 1,626,553 x 4,294,967,296 / 600 = 11,643,319,900,351 hashes per second = 11.6 terahashes per second). That's how much hashpower you need to pull off a 51% attack. Good luck! Grin

Will pretend to do unverifiable things (while actually eating an enchilada-style burrito) for bitcoins: 1K6d1EviQKX3SVKjPYmJGyWBb1avbmCFM4
Revalin
Hero Member
*****
Offline Offline

Activity: 728


165YUuQUWhBz3d27iXKxRiazQnjEtJNG9g


View Profile
April 11, 2012, 05:20:00 AM
 #3

tl;dr: it takes (difficulty * 232) hashes to solve a block on average.

      War is God's way of teaching Americans geography.  --Ambrose Bierce
Bitcoin is the Devil's way of teaching geeks economics.  --Revalin 165YUuQUWhBz3d27iXKxRiazQnjEtJNG9g
Red Emerald
Hero Member
*****
Offline Offline

Activity: 742



View Profile WWW
April 11, 2012, 06:42:50 AM
 #4

tl;dr: it takes (difficulty * 232) hashes to solve a block on average.
2 paragraphs needed a tl;dr?

Pieter Wuille
Legendary
*
qt
Offline Offline

Activity: 1036


View Profile WWW
April 11, 2012, 10:36:33 AM
 #5

difficulty * 2^48 / 65535, actually Smiley

aka sipa, core dev team

Tips and donations: 1KwDYMJMS4xq3ZEWYfdBRwYG2fHwhZsipa
Foxpup
Legendary
*
Offline Offline

Activity: 1708



View Profile
April 11, 2012, 11:10:04 AM
 #6

difficulty * 2^48 / 65535, actually Smiley
Yes, that 0.0015% makes all the difference. Wink

Will pretend to do unverifiable things (while actually eating an enchilada-style burrito) for bitcoins: 1K6d1EviQKX3SVKjPYmJGyWBb1avbmCFM4
worldinacoin
Hero Member
*****
Offline Offline

Activity: 658



View Profile WWW
April 14, 2012, 09:53:06 AM
 #7

Difficulty is the maximum possible hash target divided by the current hash target. The average time to find a block (in seconds) is equal to the current difficulty times 2^32 (4,294,967,296) divided by your hashrate (in hashes per second) (eg, if your hashrate is 1 Ghash/s = 1,000,000,000 hashes per second then the average time it will take you to find a block is (1,626,553 x 4,294,967,296 / 1,000,000,000 = 6,985,992 seconds = 80 days).

Since the difficulty is adjusted so that miners find blocks on average once every 10 minutes (600 seconds), the total hashpower of the network is equal to the difficulty times 2^32 divided by 600 (eg, 1,626,553 x 4,294,967,296 / 600 = 11,643,319,900,351 hashes per second = 11.6 terahashes per second). That's how much hashpower you need to pull off a 51% attack. Good luck! Grin

Thanks a million, I still do not get you on this part

Since the difficulty is adjusted so that miners find blocks on average once every 10 minutes (600 seconds), the total hashpower of the network is equal to the difficulty times 2^32 divided by 600 (eg, 1,626,553 x 4,294,967,296 / 600 = 11,643,319,900,351 hashes per second = 11.6 terahashes per second). That's how much hashpower you need to pull off a 51% attack. Good luck! Grin

Why is it 11 tera hashes for 51%, shouldn't it be 100% already?
Revalin
Hero Member
*****
Offline Offline

Activity: 728


165YUuQUWhBz3d27iXKxRiazQnjEtJNG9g


View Profile
April 14, 2012, 10:06:15 AM
 #8

If the rest of the network has 11.6 TH, and you have 11.6 TH, you have 50%.  If you go up to 23.2 TH, you'd have 67%.

      War is God's way of teaching Americans geography.  --Ambrose Bierce
Bitcoin is the Devil's way of teaching geeks economics.  --Revalin 165YUuQUWhBz3d27iXKxRiazQnjEtJNG9g
wachtwoord
Legendary
*
Offline Offline

Activity: 1484



View Profile WWW
April 14, 2012, 10:10:52 AM
 #9

difficulty * 2^48 / 65535, actually Smiley
Yes, that 0.0015% makes all the difference. Wink

What 0.0015% difference? 65535=2^16 so:

2^48 / 65535 = 2^48 / 2^16 = 2^(48-16)= 2^32

Showing the division does show better where the numbers come from though Smiley

Revalin
Hero Member
*****
Offline Offline

Activity: 728


165YUuQUWhBz3d27iXKxRiazQnjEtJNG9g


View Profile
April 14, 2012, 10:15:34 AM
 #10

65535=2^16

Nope.  2^16 = 65536 .

      War is God's way of teaching Americans geography.  --Ambrose Bierce
Bitcoin is the Devil's way of teaching geeks economics.  --Revalin 165YUuQUWhBz3d27iXKxRiazQnjEtJNG9g
Sukrim
Legendary
*
Offline Offline

Activity: 1848


View Profile
April 14, 2012, 12:19:26 PM
 #11

What 0.0015% difference? 65535=2^16
A multiple of 2 that ends in 5? Roll Eyes

That's not the kind of math I learned in school... Tongue

https://bitfinex.com <-- leveraged trading of BTCUSD, LTCUSD and LTCBTC (long and short) - 10% discount on fees for the first 30 days with this refcode: x5K9YtL3Zb
Mail me at Bitmessage: BM-BbiHiVv5qh858ULsyRDtpRrG9WjXN3xf
worldinacoin
Hero Member
*****
Offline Offline

Activity: 658



View Profile WWW
April 14, 2012, 01:09:20 PM
 #12

I think he means 0 to 65535
Foxpup
Legendary
*
Offline Offline

Activity: 1708



View Profile
April 14, 2012, 01:51:27 PM
 #13

I think he means 0 to 65535

2^16 is always 65536, regardless of whether you count from 0 or from 1. The number is exactly 2^48/(2^16-1). I thought I could simplify things by saying it was 2^32, but that plan didn't seem to work as intended. Roll Eyes

Will pretend to do unverifiable things (while actually eating an enchilada-style burrito) for bitcoins: 1K6d1EviQKX3SVKjPYmJGyWBb1avbmCFM4
wachtwoord
Legendary
*
Offline Offline

Activity: 1484



View Profile WWW
April 14, 2012, 03:20:29 PM
 #14

Yes I see I have been number blind. I actually read 65536 so scrap that Smiley

2^48/((2^16)-1) is indeed the exact number

Pages: [1]
  Print  
 
Jump to:  

Sponsored by , a Bitcoin-accepting VPN.
Powered by MySQL Powered by PHP Powered by SMF 1.1.19 | SMF © 2006-2009, Simple Machines Valid XHTML 1.0! Valid CSS!