On Sat, Jan 19, 2013 at 10:47 AM, Jose Amoreira <ljmamore...@gmail.com> wrote:
>
> I defined a class, CelestialBody, that describes objects that
> represent planets in my simulation. These objects have three attributes:
> position, velocity and mass (the first two are 3D-vectors; as such, the
> number of attributes is actually 7). The many-body system is represented in
> the simulation by a list of CelestialBody objects.
>
> The dynamical state of the system is represented by a 6N (N being the number
> of planets) component array storing the components of the position and
> linear momentum of each body, and the integration procedures (odeint in this
> case) usually take this array as argument.
Working with views:
>>> import numpy as np
2 planets:
>>> system_state = np.zeros(12)
Create a view for each planet:
>>> mars, earth = [system_state[6*i:6*(i+1)] for i in range(2)]
Modify the views, which also changes the original array:
>>> mars += 1
>>> earth += 2
>>> system_state
array([ 1., 1., 1., 1., 1., 1., 2., 2., 2., 2., 2., 2.])
So you can use a CelestialSystem that has the overall state array and
CelestialBody objects that use a view on the latter. Velocity can be a
property, computed from linear momentum and mass.
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