-
Notifications
You must be signed in to change notification settings - Fork 69
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
Лидов–古在 #3113
The head ref may contain hidden characters: "\u041B\u0438\u0434\u043E\u0432\u53E4\u5728"
Лидов–古在 #3113
Conversation
@@ -0,0 +1,45 @@ | |||
#pragma once |
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Just call this file memory_orbiter.hpp
. No point in recording who provided it or what bug it was associated with. (You can have that in the comments, of course.)
date_time::Date::Ordinal(year, 1))); | ||
LOG(ERROR) << "Flowing to " << t; | ||
auto const status = ephemeris_->FlowWithFixedStep(t, *instance); | ||
if (!status.ok()) { |
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Should this be a CHECK
?
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
No, we do encounter an erroneous status (the orbiter runs into the ground at the end of 1971).
elements.argument_of_periapsis, | ||
mathematica::ExpressIn(Radian)); | ||
} | ||
// The elements e, i, and ω all vary quite a lot. |
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
The numbers would be easier to interpret if, instead of min
and max
(or in addition), you looked at the relative error between measure
and midpoint
. It's like 75% for e
and 17% for c₁
.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
I don’t think the relative errors are meaningful here.
The point (c₁, c₂) lies within a bounded region within [0, 1] × [-3/5, 2/5] (depicted in [Лид61, p. 29], [LC62, p. 745]).
Relative errors clearly aren’t relevant for the angles, and for the eccentricity the fact that the orbit goes to infinity at e=1, not e=0, should make it clear that the relative error of e is, if anything, the reverse of what we care about.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
How do you demonstrate that something is constant if you have lots of measurements with noise? By looking at its statistical elements. If you are not happy with a cheesy relative error, please do a proper statistical analysis. (We have tools to do that in testing_utilities\statistics.hpp
.)
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
As discussed, what we care about is the absolute scale of the variations; they are not really noise, but they are very small compared to the size of the region given in Рис. 1.
retest this please |
This test showcases the Лидов–古在 mechanism, and thus fixes #1119.



The relevant elements vary as follows:
The eccentricity–inclination exchange is evidenced by the following graph:
The other conserved quantity (which relates all three elements) is also constant: the argument of the periapsis governs that exchange.