apps121025_test_liouville.app03_multiple

Multiple particle, trying to estimate the amount of work.

500 particle tracing takes ~7.568 sec for my iMac. 1 hr will calculate 240000 particles.

I am still not very sure how much particles needed.

''' Multiple particle, trying to estimate the amount of work.

500 particle tracing takes ~7.568 sec for my iMac.
1 hr will calculate 240000 particles.

I am still not very sure how much particles needed.

'''
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.patches as mp

from .app02_setup import kep_particle

def main():

    ### Reference condition at t=0.  For 2D.
    pos0ref = np.array([4.5e8, 0, 0])
    vel0ref = np.array([-10e3 * 0.5, 10e3 * np.sqrt(3./4), 0])

    ### Reference condition at t=3e5.
    pos1ref, vel1ref = kep_particle(pos0ref, vel0ref)

    posdel = np.array([5e6, 5e6, 0])    # Dr at t=0
    veldel = np.array([10., 10., 0])      # Dv at t=0

    drdv = posdel[0] * posdel[1] * veldel[0] * veldel[1]
    print(drdv)

    npart = 500

    pos0list = np.zeros([3, npart])
    pos1list = np.zeros([3, npart])

    vel0list = np.zeros([3, npart])
    vel1list = np.zeros([3, npart])

    for n in range(npart):  ###  Test particles
        ### Calculate the position and velocity
        ### from the parameters defined above.
        ### Position (and velocity) should have
        ### the uniformly random from pos0ref \pm posdel/2.

        posx = np.random.uniform(low=-posdel[0] / 2., high=posdel[0] / 2.) + pos0ref[0]
        posy = np.random.uniform(low=-posdel[1] / 2., high=posdel[1] / 2.) + pos0ref[1]
        velx = np.random.uniform(low=-veldel[0] / 2., high=veldel[0] / 2.) + vel0ref[0]
        vely = np.random.uniform(low=-veldel[1] / 2., high=veldel[1] / 2.) + vel0ref[1]

        pos = np.array([posx, posy, 0])
        vel = np.array([velx, vely, 0])

        pos0list[:, n] = pos
        vel0list[:, n] = vel

        pos1, vel1 = kep_particle(pos, vel)
        pos1list[:, n] = pos1
        vel1list[:, n] = vel1

    plt.figure()
    plt.subplot(221)
    plt.scatter(pos0list[0, :] - pos0ref[0], pos0list[1, :] - pos0ref[1])
    plt.subplot(222)
    plt.scatter(vel0list[0, :] - vel0ref[0], vel0list[1, :] - vel0ref[1])
    plt.subplot(223)
    plt.scatter(pos1list[0, :] - pos1ref[0], pos1list[1, :] - pos1ref[1])
    drbox = mp.Rectangle([0, 0], posdel[0], posdel[1], color='r')
    plt.gca().add_patch(drbox)
    plt.subplot(224)
    plt.scatter(vel1list[0, :] - vel1ref[0], vel1list[1, :] - vel1ref[1])
    dvbox = mp.Rectangle([0, 0], veldel[0], veldel[1], color='r')
    plt.gca().add_patch(dvbox)


    plt.savefig('app03_multiple.png')
    

if __name__ == "__main__":
    import time
    t0 = time.time()
    main()
    print('Time ellapsed', time.time() - t0)