Is there a maximum factor by which difficulty can change?

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I seem to recall, long ago, being told that difficulty couldn't change more than a certain amount at each retarget, but I can't seem to find what that factor is (or even confirmation that such a factor exists) no matter how hard I google. Does such a factor exist and if so what is its value?

David Perry

Posted 2012-06-22T23:49:54.983

Reputation: 13 848

Answers

11

The difficulty never changes by more than a factor of 4 (except for in a special case that only applies on testnet).

The code that enforces this is here.

Chris Moore

Posted 2012-06-22T23:49:54.983

Reputation: 13 952

8

Well doesn't that figure, the moment I ask the question my google-fu kicks in.

This wiki article states:

A single retarget never changes the target by more than a factor of 4 either way to prevent large changes in difficulty.

David Perry

Posted 2012-06-22T23:49:54.983

Reputation: 13 848

Ah, gotta love moments like this! ;)ThePiachu 2012-06-23T00:08:08.857

Yeah, I seriously think there's something about the act of phrasing a question for SE that activates some hidden bit of gray matter and creates superior search terms. It's not so annoying when it's an hour later, this one was mere seconds :PDavid Perry 2012-06-23T00:13:12.873

1Well, it's still a good question and a good answer.ThePiachu 2012-06-23T00:27:12.093

Interesting that the article would consider a change from the currently difficult of 1,726,567 to either 5,000,000 or 500,000 as not being a large change... I guess it's considering it from a logarithmic perspective?Highly Irregular 2012-06-23T01:03:21.177