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Known Errors in XStar

XStar hasn't been touched since around 1996, but only a few bugs have been found since then. None of them are serious, but here is a list of them.

  • In some rare cases, the buffer used to hold the star trails will completely fill up. This causes XStar to go into an infinte loop. In my experience, this bug will be triggered after no more than a week or so of running it 24 hours/day.
  • In section 1.5.5 of the documentation, the "sling shot" effect is covered. While the discussion basically correct, it turns out that the shown won't work. While the "space probe" can pass either in front or behind the planet that it is sling shooting off, the actual paths are more complex and harder to show without several pictures. This is a case of over simplification.
  • In section 4.1 of the documentation, places that mention the commutative property of addition should be talking about the associative property. When two stars collide, the force calculations for some stars will be incorrect. The collisions really should be handled as a seperate pass, or some stars will end up either not getting the force from one of the merged stars applied to it, or it will be applied twice.

    In practice, this error is probably smaller than the error caused by having to restart the multi-step evaluation functions and losing the "history" of the star paths.

  • In section 2.1.3, the figure that describes the Runge-Kutta method is Figure 19, not Figure 22.

While I'm not an expert, I believe the information on this page is correct. Please send suggestions and corrections to the webmaster.
This web site runs on 100% Open Source Software. This web page was last changed on 05/15/2004 at 15:15:36.