def uniform_distribution(N, R, koeff=1./3.):
#koeff nulemia pasiskirstyma.
x_stars, y_stars, z_stars = vector_projection(N, np.power(np.random.sample(N), koeff) * R)
bodies = Bodies()
bodies.r = np.transpose(np.array([x_stars, y_stars, z_stars]))
bodies.m = np.ones(N) * constants.SOLAR_MASS
bodies.v = np.zeros(bodies.r.shape)
M = np.sum(bodies.m)
ro = M/(4./3.*np.pi*R**3)
print "Expected collapse time : {:e}".format(np.sqrt(3*np.pi/32./constants.G/ro))
return bodies, 'dist{:.3}'.format(koeff)
def plummer(N, r_pl):
M_min = 0.08 # min zvaigzdes mase
M_max = 100 # max zvaigzdes mase
mStars = IMF_salpeter(N, M_min, M_max) * constants.SOLAR_MASS
rStars = np.sort(distance_plummer(N, r_pl))
xStars, yStars, zStars = vector_projection(N, rStars)
vStars = velocity_kepler(N, mStars, rStars)
v_xStars, v_yStars, v_zStars = vector_projection(N, vStars)
bodies = Bodies()
bodies.r = np.transpose(np.array([xStars, yStars, zStars]))
bodies.m = np.array(mStars)
bodies.v = np.transpose(np.array([v_xStars, v_yStars, v_zStars]))
return bodies, 'plummer'
def uniform_sphere(N, R):
phi = np.random.random((N)) * 2.0 * np.pi
costheta = (np.random.random((N)) - 0.5) * 2.0
u = np.random.random((N))
theta = np.arccos(costheta)
r = R * u**(1.0/3.0)
x_stars = r * np.sin(theta) * np.cos(phi)
y_stars = r * np.sin(theta) * np.sin(phi)
z_stars = r * np.cos(theta)
bodies = Bodies()
bodies.r = np.transpose(np.array([x_stars, y_stars, z_stars]))
bodies.m = np.ones(N) * constants.SOLAR_MASS
bodies.v = np.zeros(bodies.r.shape)
M = np.sum(bodies.m)
ro = M/(4./3.*np.pi*R**3)
print "Expected collapse time : {:e}".format(np.sqrt(3*np.pi/32./constants.G/ro))
return bodies, 'sphere'
