Phoenixcoin Hard Fork \#4 Discussion
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[quote name=“groll” post=“31780” timestamp=“1382163406”]
I have try to find a good function for hashrate but still don’t have a perfect one. the one you use converge by itself so a constant diff would converge, we know this is not true.
ahasrate like =($Z27*0.0288)-(AQ27-$Z27)/5 seems to make a not too bad formula. sorry no time o finish my version of it tonight :(
[/quote]I know my hash rate estimation formula isn’t very good and may be useful for short periods of time only. Needs more randomisation. Although it shows well how various averaging models can settle at +/- 1% of block time.
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here in attachment you will find Ghostlander simulation with a more agressive hashrate change vs diff that don’t converge. anything without damping oscillate. 100-500 or 126/504 seesm to be the good choice with .25 or possibly an even more aggressive damping
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Groll, there is a mistake in the formula for 100 blocks averaging which calculates incorrect limiting:
=MIN(Z51*1,02;MAX(Z51*0,98;1/((V12+W12+X12+Y12+Z12)/(5*150))*Z11))
Z11 must be instead of Z51. It oscillates much stronger after the fix. Also Z23 instead of Z63 for 20/100.
20 blocks averaging with 0.1 damping shows excellent results because the base data in Z column is aligned perfectly. If we add 10% to the difficulty in Z55, it takes 10 retargets to stabilise within 1%. 0.25 damping is much faster.
I have added one 2x surge and one 0.5x dip in 10 retargets after the surge to see how our models react to such conditions. 100 and 500 blocks averaging are very bad. 100/500 is better significantly, but still not good enough. 100/500 with 0.50 or 0.67 damping oscillate too much. 100/500 with 0.25 is very good. I have added 100/500 with 0.33 to the simulation. Almost as good as 0.25, much better than 0.50. I like it.
Enuma, it’s too complicated. We need something simple to feed Calc/Excel with. Groll’s one is good.
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you are right i have not really take care to verify too much the non damped one as they are not working well and yes the 20 is broken by the formula and i was screwed as i calculate on time and you on hashrate so moving the Z column makes some row going to a different value than others as they have different formula, representing with an expected value on Z the same reality. I played a lot on A-Y especially on U-Y to see the effects before and send a working one with FTC values. but this altered futur is good to see what happen also
with 2% retarget every 20 and 100/500 sampling more damping can also work well .1 for example is fine as it’s going to retarget often so moving a bit more slowly would work great even if large change occur. as if larger then 20% occur it goes to max and if lower then it just move 1/10 of the error each time. the error is calculate on 5 and 25 sample so a 20 blocs deviation would be include several time in the calculation. it’s the reason we see some echo of the past in the curves.
I like the 20/100/500 with .1 damping as small immediate effect of change can be seen and the overall effect of 20 if completely off is minimized by both other sampling and the damping. my second choice would be 100/500 with .1 but anything in .25 or more damping (
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I have given it a bit of further thinking and testing with 0.1 damping. I have come to the conclusion that 100/500 0.1 is a better choice than 100/500 0.25 given 2% over 20 blocks. 20/100/500 0.1 shows a very little improvement over 100/500 0.1 which is not worth a higher time warp vulnerability. Now I’m going to write the code.
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v0.6.5.0 is near complete. The code is at [url=https://github.com/ghostlander/Phoenixcoin]GitHub[/url] (note the new repository name). It has passed all tests on the testnet today. No binaries at this moment, but you can compile the code yourself as usual. You can use the Qt GUI of the previous release until I finish with it. You can also join the testnet with -addnode=146.185.140.182:19555 to test drive the new settings before the official release.
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This is the summary of the 4th hard fork. Even though the PXC network has peaked almost at 200MH/s today, our difficulty adjustment algorithm works very well. You can see it following the network hash rate softly in the graph below.
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Excellent work Ghostlander. You have done an upstanding job of turning Phoenixcoin around.
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Very interesting work, I loved the chart. Can I resurrect my 2 phoenix coins or is this a new network?
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[quote name=“wrapper0feather” post=“37154” timestamp=“1385639667”]
Very interesting work, I loved the chart. Can I resurrect my 2 phenix coins or is this a new network?
[/quote]The coins are the same. Install the latest client, download the block chain and you’re good to go as usual.
