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jonathan
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Calling Planetary EphemerisSimulink Block From .m file. The resulting output is unclear.

Asked by jonathan
on 8 May 2014
Latest activity Commented on by jonathan
on 8 May 2014
Tjd=juliandate(2000,0,0);
options = simset('SrcWorkspace','current');
[X, V] = sim('Planetary_Epmemeris',Tjd,options);
I am trying to get ephemeris data (position and velocity) for specified celestial bodies. The outputs that I am getting are not the three element cartisian vectors I assumed I would get for position and velocity. V: double and X: double. I have no idea what this output means, and the documentation gives no details on how to interpret it.

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1 Answer

Answer by Ryan G
on 8 May 2014

Did you try starting from the example?
Implement the position and velocity for Saturn with respect to the Solar System barycenter for noon on January 1, 2000 using DE421 and AU units:
[position,velocity] = planetEphemeris([2451544.5 0.5],... 'SolarSystem','Saturn','421','AU') position = 6.3993 6.1720 2.2738 velocity = -0.0043 0.0035 0.0016

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Hey, look at that! I hadn't seen that there was a Matlab function for this, so I was useing SIM to call the block. Thanks! Any idea on the accuracy of these results?

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