It is neat to see some of the old work done in the field, this looks like a pretty classic treatment of the topic. It looks like they were using a fourth-order Runge-Kutta integrator, which would likely limit long term integrations accuracy (though looks sufficient for their use case). Many algorithms I have seen typically use much higher order integration methods to beat down the accumulation of numerical error.

Source: Working on my PhD in orbital mechanics of asteroids/comets, here are my open source (python/rust) orbital integration tools: https://github.com/dahlend/kete

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keepamovin 2 days ago | parent | next [-]

That is cool! I encourage you to post as a Show HN with a comment explaining more if you want

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wiz21c 2 days ago | parent | prev [-]

I'm interested. Could you give examples ?

	▲	ddahlen 2 days ago \| parent [-]
		https://www.cambridge.org/core/journals/international-astron... Here is a heavily used method in astronomy, this involves a higher order polynomial expansion than RK4. This method has been extended a few times, my code uses a variation of it, and I know of several other projects which are also descended from it.