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If anyone is interested, I have prepared
alternative Integrators that can be added to the systemic console and
ares quite a
bit faster than the built-in RK5 and Hermite 4th order methods.
Version 1.2 of a Yoshida integrator is now available from the download
below.
The integrator now calculates its own fully variable step time based
on the relative positions and velocities of the planets. This slows
down the integrator a bit but makes it much more reliable and able to
deal with quite high eccentricities. It should give results the same
as the built-in integrators in almost all situations. It runs at about
5 times the speed of the built-in Hermite method.
Version 1.0 of the New Hermite
integrator is also available. It may be marginally less accurate than
the Yoshida in complex systems with high eccentricity. It runs at
about 9 times the speed of the built-in Hermite method.
The implementations have been kept as simple as possible but in
recent tests I can find no significant difference in results between
the Yoshida and the built-in RK5 and Hermite methods. Small
differences between the New and built-in Hermite results have been
seen in complex, high eccentricity systems. Collision detection is very simple - if any
two bodies come within 0.0005AU then a collision is signalled. Maximum
number of bodies is 20.
To use them:
Create a directory called "Integrators" in your systemic directory.
Download the
Yoshida.class file and place it in the Integrators directory.
Download the Hermite.calss
file and place it in the integrators directory.
Download the
integrators.ini
file and place it in your systemic directory.
Let me know how you get on. (I am user Pandora
on the systemic website).
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