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Groups > sci.physics.relativity > #384802
| From | HGW <hw@...> |
|---|---|
| Newsgroups | sci.physics.relativity |
| Subject | Re: Interesting problem |
| Date | 2016-06-02 09:40 +1000 |
| Organization | Aioe.org NNTP Server |
| Message-ID | <ninrpn$1jhl$1@gioia.aioe.org> (permalink) |
| References | (15 earlier) <3edb149f-6a4a-4118-985c-85782403ded7@googlegroups.com> <niflaf$cf4$1@gioia.aioe.org> <61d916ae-3ee6-4360-94c4-dd4b9c6ca6cf@googlegroups.com> <nijqjm$3vh$1@gioia.aioe.org> <44665795-a52b-468a-910f-aee104e7f463@googlegroups.com> |
On 01/06/16 01:40, alsor@interia.pl wrote:
> W dniu wtorek, 31 maja 2016 12:55:54 UTC+2 użytkownik HGWilson, DSc. napisał:
>> On 31/05/16 09:27, alsor@interia.pl wrote:
>>> W dniu niedziela, 29 maja 2016 23:01:07 UTC+2 użytkownik HGWilson, DSc. napisał:
>>
>>> forceg(a, y, sqr(h)/12); // g + h^2/48 grad(g^2); grad g^2 = 4 g^2 ...
>>> // v2 = v1 + a*h 2/3; r1 = r1 + v2 h/2;
>>> for(int i = 0; i < nB; i++)
>>> {
>>> y[i].v.addm(a[i], h*(2.0/3));
>>> y[i].r.addm(y[i].v, h2);
>>> }
>>>
>>> force(a,y,nB);
>>> for(int i = 0; i < nB; i++)
>>> {
>>> y[i].v.addm(a[i], h6);
>>> }
>>> }
>>
>> I think there might be an easier and more straightforward way using
>> computers but it might be a bit slower. Knowing the final error after
>> one cycle, it should be possible to empirically correct each step until
>> the error disappears.
>
> This method has order of 4, thus it's thousands
> times faster than any 2-order, like the Euler-Cromer, Verlet, Frog, etc.
>
>
> Simply: use a bigger time step for higher order method.
>
> for 4-order optimal step is about: h = 1/1000 of the orbital period,
> thus for Mercury it's 88days/1000 =~ day / 12 = 2 hours.
>
>
> for 2-order the step should be squared:
> h = 1/1000000... = 7 seconds for this case!
> 4/2 = 2.
The iteration time interval can be easily adjusted in my current method.
I have found that about 40000 points produces a pretty accurate ellipse.
But not good enough to simulate precession.
I reckon I can reduce that error to near zero by applying a simple
correction at each point.
....no complicated equations...just programming factors.
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Interesting problem "HGWilson, DSc." <hgw@....> - 2016-05-26 07:05 +1000
Re: Interesting problem Poutnik <poutnik4nntp@gmail.com> - 2016-05-25 23:17 +0200
Re: Interesting problem "David (Time Lord) Fuller" <fuller.david@hotmail.com> - 2016-05-25 14:20 -0700
Re: Interesting problem "David (Time Lord) Fuller" <fuller.david@hotmail.com> - 2016-05-25 14:18 -0700
Re: Interesting problem Odd Bodkin <bodkinodd@gmail.com> - 2016-05-25 16:20 -0500
Re: Interesting problem Tom Roberts <tjroberts137@sbcglobal.net> - 2016-05-25 18:31 -0500
Re: Interesting problem "HGWilson, DSc." <hgw@....> - 2016-05-27 03:25 +1000
Re: Interesting problem Odd Bodkin <bodkinodd@gmail.com> - 2016-05-26 13:32 -0500
Re: Interesting problem HGW <hw@...> - 2016-05-27 12:15 +1000
Re: Interesting problem Odd Bodkin <bodkinodd@gmail.com> - 2016-05-27 04:26 -0500
Re: Interesting problem "HGWilson, DSc." <hgw@....> - 2016-05-27 19:52 +1000
Re: Interesting problem Odd Bodkin <bodkinodd@gmail.com> - 2016-05-27 05:46 -0500
Re: Interesting problem "HGWilson, DSc." <hgw@....> - 2016-05-27 21:55 +1000
Re: Interesting problem Odd Bodkin <bodkinodd@gmail.com> - 2016-05-27 07:23 -0500
Re: Interesting problem Odd Bodkin <bodkinodd@gmail.com> - 2016-05-27 07:26 -0500
Re: Interesting problem "David (Time Lord) Fuller" <fuller.david@hotmail.com> - 2016-05-27 05:29 -0700
Re: Interesting problem "HGWilson, DSc." <hgw@....> - 2016-05-28 19:47 +1000
Re: Interesting problem Prokaryotic Caspase Homolog <prokaryotic.caspase.homolog@gmail.com> - 2016-05-28 04:12 -0700
Re: Interesting problem Prokaryotic Caspase Homolog <prokaryotic.caspase.homolog@gmail.com> - 2016-05-28 04:51 -0700
Re: Interesting problem alsor@interia.pl - 2016-05-28 11:27 -0700
Re: Interesting problem Prokaryotic Caspase Homolog <prokaryotic.caspase.homolog@gmail.com> - 2016-05-28 14:01 -0700
Re: Interesting problem alsor@interia.pl - 2016-05-28 15:10 -0700
Re: Interesting problem "HGWilson, DSc." <hgw@....> - 2016-05-29 09:35 +1000
Re: Interesting problem alsor@interia.pl - 2016-05-29 10:35 -0700
Re: Interesting problem "HGWilson, DSc." <hgw@....> - 2016-05-30 07:01 +1000
Re: Interesting problem Prokaryotic Caspase Homolog <prokaryotic.caspase.homolog@gmail.com> - 2016-05-29 15:22 -0700
Re: Interesting problem alsor@interia.pl - 2016-05-30 13:05 -0700
Re: Interesting problem alsor@interia.pl - 2016-05-30 16:27 -0700
Re: Interesting problem "HGWilson, DSc." <hgw@....> - 2016-05-31 20:56 +1000
Re: Interesting problem alsor@interia.pl - 2016-05-31 08:40 -0700
Re: Interesting problem HGW <hw@...> - 2016-06-02 09:40 +1000
Re: Interesting problem alsor@interia.pl - 2016-06-02 11:53 -0700
Re: Interesting problem Prokaryotic Caspase Homolog <prokaryotic.caspase.homolog@gmail.com> - 2016-05-31 04:25 -0700
Re: Interesting problem mlwozniak@wp.pl - 2016-05-31 04:58 -0700
Re: Interesting problem "HGWilson, DSc." <hgw@....> - 2016-06-01 06:31 +1000
Re: Interesting problem Odd Bodkin <bodkinodd@gmail.com> - 2016-05-31 16:30 -0500
Re: Interesting problem HGW <hw@...> - 2016-06-02 09:44 +1000
Re: Interesting problem JanPB <filmart@gmail.com> - 2016-05-31 14:58 -0700
Re: Interesting problem "HGWilson, DSc." <hgw@....> - 2016-06-01 06:24 +1000
Re: Interesting problem Prokaryotic Caspase Homolog <prokaryotic.caspase.homolog@gmail.com> - 2016-06-01 06:23 -0700
Re: Interesting problem Odd Bodkin <bodkinodd@gmail.com> - 2016-06-01 11:11 -0500
Re: Interesting problem HGW <hw@...> - 2016-06-02 09:47 +1000
Re: Interesting problem Prokaryotic Caspase Homolog <prokaryotic.caspase.homolog@gmail.com> - 2016-06-01 18:50 -0700
Re: Interesting problem alsor@interia.pl - 2016-06-02 12:07 -0700
Re: Interesting problem alsor@interia.pl - 2016-06-01 08:59 -0700
Re: Interesting problem HGW <hw@...> - 2016-06-02 10:09 +1000
Re: Interesting problem Odd Bodkin <bodkinodd@gmail.com> - 2016-05-29 13:52 -0500
Re: Interesting problem "HGWilson, DSc." <hgw@....> - 2016-05-30 07:09 +1000
Re: Interesting problem Sam Wormley <swormley1@gmail.com> - 2016-05-29 16:26 -0500
Re: Interesting problem Fabian Russell <fb@zen.info> - 2016-05-30 04:25 +0000
Re: Interesting problem "HGWilson, DSc." <hgw@....> - 2016-05-31 21:00 +1000
Re: Interesting problem Fabian Russell <fb@zen.info> - 2016-05-31 22:46 +0000
Re: Interesting problem HGW <hw@...> - 2016-06-02 09:32 +1000
Re: Interesting problem Prokaryotic Caspase Homolog <prokaryotic.caspase.homolog@gmail.com> - 2016-05-27 05:34 -0700
Re: Interesting problem "David (Time Lord) Fuller" <fuller.david@hotmail.com> - 2016-05-27 05:40 -0700
Re: Interesting problem "David (Time Lord) Fuller" <fuller.david@hotmail.com> - 2016-05-27 05:43 -0700
Re: Interesting problem rotchm <rotchm@gmail.com> - 2016-05-27 06:40 -0700
Re: Interesting problem Prokaryotic Caspase Homolog <prokaryotic.caspase.homolog@gmail.com> - 2016-05-27 07:42 -0700
Re: Interesting problem rotchm <rotchm@gmail.com> - 2016-05-27 06:36 -0700
Re: Interesting problem Odd Bodkin <bodkinodd@gmail.com> - 2016-05-27 09:01 -0500
Re: Interesting problem "HGWilson, DSc." <hgw@....> - 2016-05-28 20:04 +1000
Re: Interesting problem Prokaryotic Caspase Homolog <prokaryotic.caspase.homolog@gmail.com> - 2016-05-28 04:34 -0700
Re: Interesting problem Fabian Russell <fb@zen.info> - 2016-05-27 22:03 +0000
Re: Interesting problem "HGWilson, DSc." <hgw@....> - 2016-05-28 20:10 +1000
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