Re: More re sorting TLE's

Bjoern Gimle (b_gimle@algonet.se)
Thu, 3 Oct 1996 22:28:38 +0200 (MET DST)

>
>Someone wrote recently:
>>
>>I use tlemop for DOS, its a little slow if you have a slow hard drive cuz
>>of how it organizes its data but it does the job and has some good sorting
>
Stephen Thompson <SThompson@esiusa.com> explained:

>Slow performance of TLEMOP may be due to a misunderstanding of the way it 
>was expected to be used.
....
>For most purposes the 'right way' to use TLEMOP is with the "save the 
>workfile' switch set. ....
>Once it is in place, updating the 'database' AKA 'the workfile'  from 
>new TLE collections, saved Email messages etc is quite efficient.
>
> I have not tried QSORT, so I would be interested in hearing the results
> of a level ground race involving a few thousand elements.
>
I tried an earlier version, to maintain a 4000+ elset. I grasped the idea
of the workfile, and believe I used it correctly. I found it too slow, and
the elset file of 630 kb turned into a workfile of 4+ MB, which seemed to
keep growing. I have not tested the newer version, because I want to keep
all old elsets for future analysis of orbits and UnId's, and haven't seen
any tle manager doing that.

Still, I would gladly benchmark tlemop against qsort, which I use to sort
my database, then a program of my own to read it sequentially to discard
duplicates and save older elsets.

On my 486-50DX PC notebook with a 350 MB drive, running Windows 3.11
(with 10 active Win programs, 2 DOS windows running SkyMap, plus qsort
and Program Manager) I sorted a 4347 record, 660 kb database, from
descending ndot2 to ascending USSPACECOM catalog number, in 25 seconds.

Sorting the resulting ascending USSPACECOM file into descending USSPACECOM
took 26 seconds - no significant difference.

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