📅 Original date posted:2016-03-08
📝 Original message:This seems unnecessarily complicated ("don't use cannon to kill mosquito"
kind of thing). If the community were interested in a realtime hashrate
rebalancing proposal one could simply adjust difficulty at each new block
using the current method.
If faster relaxation in case of adversity is required, it suspect that it
would suffice to perform a weighted average of the previous 2016 blocks
instead of the standard averaging that is currently done. It should be
possible to find an optimal weighting based on historical interblock timing
data. I look into it over the next couple of days.
dpinna
> ------------------------------
>
> Message: 3
> Date: Tue, 8 Mar 2016 22:05:07 +0000
> From: Bob McElrath <bob_bitcoin at mcelrath.org>
> To: Dave Hudson <dave at hashingit.com>
> Cc: bitcoin-dev at lists.linuxfoundation.org
> Subject: Re: [bitcoin-dev] Hardfork to fix difficulty drop algorithm
> Message-ID: <20160308220507.GA4388 at mcelrath.org>
> Content-Type: text/plain; charset=us-ascii
>
> Dave Hudson via bitcoin-dev [bitcoin-dev at lists.linuxfoundation.org] wrote:
> > I think the biggest question here would be how would the difficulty
> > retargeting be changed? Without seeing the algorithm proposal it's
> difficult
> > to assess the impact that it would have, but my intuition is that this is
> > likely to be problematic.
>
> I have no comment on whether this will be *needed* but there's a simple
> algorithm that I haven't seen any coin adopt, that I think needs to be: the
> critically damped harmonic oscillator:
>
> http://mathworld.wolfram.com/CriticallyDampedSimpleHarmonicMotion.html
>
> In dynamical systems one does a derivative expansion. Here we want to
> find the
> first and second derivatives (in time) of the hashrate. These can be
> determined
> by a method of finite differences, or fancier algorithms which use a
> quadratic
> or quartic polynomial approximation. Two derivatives are generally all
> that is
> needed, and the resulting dynamical system is a damped harmonic oscillator.
>
> A damped harmonic oscillator is basically how your car's shock absorbers
> work.
> The relevant differential equation has two parameters: the oscillation
> frequency
> and damping factor. The maximum oscillation frequency is the block rate.
> Any
> oscillation faster than the block rate cannot be measured by block times.
> The
> damping rate is an exponential decay and for critical damping is twice the
> oscillation frequency.
>
> So, this is a zero parameter, optimal damping solution for a varying
> hashrate.
> This is inherently a numeric approximation solution to a differential
> equation,
> so questions of approximations for the hashrate enter, but that's all.
> Weak
> block proposals will be able to get better approximations to the hashrate.
>
> If solving this problem is deemed desirable, I can put some time into
> this, or
> direct others as to how to go about it.
>
> --
> Cheers, Bob McElrath
>
> "For every complex problem, there is a solution that is simple, neat, and
> wrong."
> -- H. L. Mencken
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20160309/9e70ecd6/attachment.html>;
Daniele Pinna [ARCHIVE] /
npub16z…jg59c
2023-06-07 17:49:49
in reply to nevent1q…wtcn
Author Public Key
npub16z2msvydkmd6xsjyrggnavcwrlpevfwq74x5avxrkg2dpq7cg6js5jg59cPublished at
2023-06-07 17:49:49Event JSON
{
"id": "6d03b11f8fdb21bdc38697093746914228d68c6acefcba5baa03a6f49f6d99eb",
"pubkey": "d095b8308db6dba342441a113eb30e1fc39625c0f54d4eb0c3b214d083d846a5",
"created_at": 1686160189,
"kind": 1,
"tags": [
[
"e",
"3df829167f4ab2259a749bcc729164d6101d33649f35d263b27d6f04e839d58f",
"",
"reply"
],
[
"p",
"a23dbf6c6cc83e14cc3df4e56cc71845f611908084cfe620e83e40c06ccdd3d0"
]
],
"content": "📅 Original date posted:2016-03-08\n📝 Original message:This seems unnecessarily complicated (\"don't use cannon to kill mosquito\"\nkind of thing). If the community were interested in a realtime hashrate\nrebalancing proposal one could simply adjust difficulty at each new block\nusing the current method.\n\nIf faster relaxation in case of adversity is required, it suspect that it\nwould suffice to perform a weighted average of the previous 2016 blocks\ninstead of the standard averaging that is currently done. It should be\npossible to find an optimal weighting based on historical interblock timing\ndata. I look into it over the next couple of days.\n\ndpinna\n\n\n\n\n\u003e ------------------------------\n\u003e\n\u003e Message: 3\n\u003e Date: Tue, 8 Mar 2016 22:05:07 +0000\n\u003e From: Bob McElrath \u003cbob_bitcoin at mcelrath.org\u003e\n\u003e To: Dave Hudson \u003cdave at hashingit.com\u003e\n\u003e Cc: bitcoin-dev at lists.linuxfoundation.org\n\u003e Subject: Re: [bitcoin-dev] Hardfork to fix difficulty drop algorithm\n\u003e Message-ID: \u003c20160308220507.GA4388 at mcelrath.org\u003e\n\u003e Content-Type: text/plain; charset=us-ascii\n\u003e\n\u003e Dave Hudson via bitcoin-dev [bitcoin-dev at lists.linuxfoundation.org] wrote:\n\u003e \u003e I think the biggest question here would be how would the difficulty\n\u003e \u003e retargeting be changed? Without seeing the algorithm proposal it's\n\u003e difficult\n\u003e \u003e to assess the impact that it would have, but my intuition is that this is\n\u003e \u003e likely to be problematic.\n\u003e\n\u003e I have no comment on whether this will be *needed* but there's a simple\n\u003e algorithm that I haven't seen any coin adopt, that I think needs to be: the\n\u003e critically damped harmonic oscillator:\n\u003e\n\u003e http://mathworld.wolfram.com/CriticallyDampedSimpleHarmonicMotion.html\n\u003e\n\u003e In dynamical systems one does a derivative expansion. Here we want to\n\u003e find the\n\u003e first and second derivatives (in time) of the hashrate. These can be\n\u003e determined\n\u003e by a method of finite differences, or fancier algorithms which use a\n\u003e quadratic\n\u003e or quartic polynomial approximation. Two derivatives are generally all\n\u003e that is\n\u003e needed, and the resulting dynamical system is a damped harmonic oscillator.\n\u003e\n\u003e A damped harmonic oscillator is basically how your car's shock absorbers\n\u003e work.\n\u003e The relevant differential equation has two parameters: the oscillation\n\u003e frequency\n\u003e and damping factor. The maximum oscillation frequency is the block rate.\n\u003e Any\n\u003e oscillation faster than the block rate cannot be measured by block times.\n\u003e The\n\u003e damping rate is an exponential decay and for critical damping is twice the\n\u003e oscillation frequency.\n\u003e\n\u003e So, this is a zero parameter, optimal damping solution for a varying\n\u003e hashrate.\n\u003e This is inherently a numeric approximation solution to a differential\n\u003e equation,\n\u003e so questions of approximations for the hashrate enter, but that's all.\n\u003e Weak\n\u003e block proposals will be able to get better approximations to the hashrate.\n\u003e\n\u003e If solving this problem is deemed desirable, I can put some time into\n\u003e this, or\n\u003e direct others as to how to go about it.\n\u003e\n\u003e --\n\u003e Cheers, Bob McElrath\n\u003e\n\u003e \"For every complex problem, there is a solution that is simple, neat, and\n\u003e wrong.\"\n\u003e -- H. L. Mencken\n\u003e\n\u003e\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20160309/9e70ecd6/attachment.html\u003e",
"sig": "96df7e2afead1a9377cd12f68ca94064052fb1dc3f15ce79ed356aebcd2d4a4d40d91ea921d4daed3c20e939e582d3ba3bdd6b87ea5e3caaa3bc5716adb80408"
}