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Re: [Orekit Developers] DeepSDP4 Potentially unreachable code



paulcefo <paulcefo@buffalo.edu> a écrit :

Gents,

Hi Paul,


I observe that the GTDS orbit determination program version that serves as the original host for the DSST also hosts SDP4.

I add that the document that describes the GTDS/SDP4 capability has been approved for public release.

This is interesting. Is this document available somewhere?

best regards,
Luc


regards,

Paul

--
Dr. Paul J. Cefola
Consultant in Aerospace Systems, Spaceflight Mechanics, & Astrodynamics
Adjunct Faculty, Dept. of Mechanical and Aerospace Engineering, University at Buffalo (SUNY)

4 Moonstone Way
Vineyard Haven, MA 02568
USA

508-696-1884 (phone on Martha's Vineyard)
978-201-1393 (cell)

paulcefo@buffalo.edu
paul.cefola@gmail.com

On 03/01/2014 1:04 pm, MAISONOBE Luc wrote:
Hi Hank,

Hank Grabowski <hank@applieddefense.com> a écrit :

I'm working on getting better code coverage on classes and have run into a
bit of a snag on the DeepSDP4 class.  There are two for loops of similiar
structure, on on line 636 and one on line 688. Both of them essentially do:

for (int j = 0; j < SECULAR_INTEGRATION_ORDER; j += 2) {
...
  if ((j + 2) < SECULAR_INTEGRATION_ORDER)  {
     ...
  }
}


With the current constant SECULAR_INTEGRATION_ORDER  set to 2 we never get
within the if loop.  Is this there for the eventuality that the secular
integration order is increased or of variable size or is this exposing an
implementation problem?

I'm not sure. It really seems to have been done for extending to
higher order, but looking back at the Vallado implementation, both in
fortran and C++, I do not find the internal if, and I don't find it in
Dundee SGP4 either. The comment in the Vallado code also states:

the specific changes are unknown because the original code was so convoluted

This internal if seems to have been there right from the beginning in
Orekit. I have tracked it at least back to commit c72f5793 in January
2007.

I guess it was extracted from some of the reference versions we used
at that time, but am unable to find it.

We should probably remove it, as we can't find were it come from since
the vallado and Dundee references do not appear to have it and it is
not reached.

Luc





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