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### Highlights from Vectorized Analytic Two Body Propagator (Kepler Universal Variables)

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# Vectorized Analytic Two Body Propagator (Kepler Universal Variables)

### Darin Koblick (view profile)

Analytic propagation routine uses universal variables to solve a single formula for all orbit types

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Description

The Keplerian universal variable two body propagation method, using the Newton-Raphson iteration technique, provides a highly efficient propagation routine which doesn't have to transform coordinate systems from cartesian to Keplerian and back again. This method will work on all orbit types (circular, eccentric, parabolic, and hyperbolic) while providing a positional error which is less than 0.5 km (this is obtained from propagation comparisons with the STK implementation of the analytic two body propagation routine).

Example function call is shown below:
>> [r,v] = keplerUniversal(r0,v0,t,mu);

Where:

Inputs:
r0 is the initial position vectors in the ECI coordinate frame of reference (km) [3xN]
v0 is the initial velocity vectors in ECI coordinate frame of reference (km/s) [3xN]
t is the time vector in seconds [1xN]
mu is the Gravitational Constant of the central body which defaults to Earth if not specified (double)

Outputs:
r is the propagated position vector in the ECI coordinate frame of reference (km) [3xN]
v is the propagated velocity vector in ECI coordinate frame of reference (km/s) [3xN]

MATLAB release MATLAB 7.11 (R2010b)
11 Apr 2012 Darin Koblick

### Darin Koblick (view profile)

John,

The zip file seems to unzip without problems. Try using either the default windows zip utility, the MATLAB command unzip(), or the free 7zip utility. If all else fails, you can view the source code here:

http://www.mathworks.com/matlabcentral/fileexchange/35566-vectorized-analytic-two-body-propagator-kepler-universal-variables/content/keplerUniversal.m

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11 Apr 2012 John Fuller

### John Fuller (view profile)

Downloaded but can't seem to unzip. Not sure if the file is corrupted, may want to check.

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