X, Y, Vx, Vy = initialize_particles(n_particles)
plot_particles(X, Y, 'coordinates_start.png')
# The main loop
for n in range(n_step):
X, Y, Vx, Vy = simulate_step(X, Y, Vx, Vy, dt)
# Print status every 100th step
if n % 100 == 0:
print "Step %5i" % (n)
# Save frame for video every 10th step
if n % 10 == 0:
video.add_frame(X, Y)
# Count the particles
if n % 5 == 0:
no_part = 0
for i in range(n_particles):
# No need to check for x_positions < 1 or y_positions since we are ALWAYS
# within the box.
if( X[i] > 0.0 ):
no_part += 1
if( n < n_step / 2 ):
particle_dist.append( no_part )
if( n > n_step / 2 ):
# for every step
for i in range(n_particles):
# if the particle is exiting the box in the x-direction, change the
# velocity
if abs(pos_x[i] + vel_x[i] * dt) > 1.0:
vel_x[i] = -vel_x[i]
if abs(pos_y[i] + vel_y[i] * dt) > 1.0:
vel_y[i] = -vel_y[i]
# make a step in time dt
pos_x[i] = pos_x[i] + vel_x[i] * dt
pos_y[i] = pos_y[i] + vel_y[i] * dt
# save a 'frame' for the video every 10 step
if n % 10 == 0:
video.add_frame(pos_x, y_pos)
# Plot the x- and y- coordinates
pylab.clf() # clear figure
pylab.plot(pos_x, pos_y, "ro")
pylab.axis((-1, 1, -1, 1))
pylab.savefig("coordinates_end.eps")
pylab.savefig("coordinates_end.png")
# Save video
pylab.clf()
video.save(1.0, "non_interacting_particles")