On Sat, 18 Mar 2006 18:36:33 -0000, "George Dishman" <[email protected]>
>"Henri Wilson" <HW@..> wrote in message
>> there is very little diference between e=0 and e=0.05
>If your code is wrong, all of the effect at e=0.05
>may be due to the error. You need to sort the bug.
You're becoming boring George.
The error is merely in the scaling of the blue velocity curve.
It has been fixed.
>>>> It does go crazy for some
>>>> reason but there is very little difference between the curves of e=0.0
>>>> and you shouldn't try to use them. The program uses a very complex
>>>> method to derive the ellipses. I didn't realize it failed at these low
>>>> eccentricities but don't worry about it. I'll look into the problem.
>>>It is symptomatic of an error in your coding so
>>>all the curves become suspect, I'll wait until
>>>you debug it before trying again.
>> I've fixed the simplified program. There was a '1/e' term. I made it a
>> 1/(e+0.1) which doesn't matter because the height scale is arbitrary
>> Il fix the other program soon.
>Perhaps it should be 'e' instead of '1/e'. The
>point is that the results are untrustable unless
>you can find the error and fix it.
Like I said, you are becoming very boring George.
>>>>>The program crashes if the number of orbits
>>>>>is >25. For the pulsar we need to use at least
>>>>>1200, probably more.
>>>> That would take days to process even on the fastest computers.
>>>> You are trying to achieve the near impossible.
>>>Nah, it should be possible to solve it analytically
>>>and do it in a fraction of a second on-line.
>> Processing time is directly proportional to the number of orbits used.
>I should have mentioned you can't solve elliptical
>motion itself analytically but I meant you could
>approximate it with a series of sines and then
>calculate the contribution for each orbit from
>those. There are still some bits that are difficult,
>you may need to solve sin(x) = ax+b but again you
>should be able to use approximations effectively.
>Even with a thousand orbits, good coding should
>get you below a second. I've spent most of my
>working life doing that sort of thing.
My program uses a very efficient method to determine velocity and direction of
movement around any orbit. It stores all the info in several large arrays. The
secret of my program is that it uses equal time steps not equal angles. It
doesn't use elliptical equations. It relies solely on a=GM/r^2. Circular orbits
are handled differently. As one would expect, there is little difference in
brightness curves for e= 0 and e= 0.05
Normally 20000 sample points is quite adequate when working below the critical
distance. Increasing that to 60000 makes virtually no difference to brightness