def midpoint(dt, tfinal):
particles, marr = fn.init_2body(0)
etot0 = fn.e_tot(particles, marr)
time = 0
x_and_v = []
while time < tfinal:
acc = fn.forces(particles, marr)
particles_mid = np.zeros((pars.Np, 2, 3))
particles_mid[:,
0, :] = particles[:, 0, :] + particles[:, 1, :] * dt / 2
particles_mid[:, 1, :] = particles[:, 1, :] + acc * dt / 2
amid = fn.forces(particles_mid, marr)
particles[:, 0, :] += particles_mid[:, 1, :] * dt
particles[:, 1, :] += amid * dt
x_and_v.append(particles.tolist())
time += dt
etot1 = fn.e_tot(particles, marr)
e_error = (etot1 - etot0) / etot0
return x_and_v, e_error
def leapfrog(dt, tfinal, tau, drag=False, init_e=0.0):
save_file = open(
"object_time_x,v,m_dt=" + str(dt) + "_tfinal=" + str(tfinal) +
"_tau=" + str(tau) + ".csv", "w")
particles, marr = fn.init_2body(init_e)
etot0 = fn.e_tot(particles, marr)
eccentricity = []
semi_major_axis = []
x_and_v = []
vkep_list = []
time_list = []
time = 0
while time < tfinal:
if drag:
acc, v_kep, v_r = fn.forces_total(particles, marr, tau)
else:
acc = fn.forces(particles, marr)
v_kep = []
particles[:, 1, :] += acc * dt / 2
particles[:, 0, :] += particles[:, 1, :] * dt
if drag:
acc, v_kep, v_r = fn.forces_total(particles, marr, tau, v_r=v_r)
else:
acc = fn.forces(particles, marr)
particles[:, 1, :] += acc * dt / 2
x_and_v.append(particles.tolist())
# print 'next'
ecc, a = fn.get_orbital_elements(particles, marr)
for i in [0, 1]:
np.savetxt(save_file,np.c_[i, time, particles[i,0,0], particles[i,0,1], particles[i,0,2], \
particles[i,1,0], particles[i,1,1], particles[i,1,2], marr[i], v_kep], delimiter=',', fmt='%.10e')
# eccentricity.append(np.sqrt(sum(ecc)**2))
# semi_major_axis.append(a)
# vkep_list.append(v_kep)
# time_list.append(time)
time += dt
if a < 0.15:
break
def leapfrog(dt, tfinal):
particles, marr = fn.init_2body(0)
etot0 = fn.e_tot(particles, marr)
time = 0
while time < tfinal:
acc = fn.forces(particles, marr)
particles[:, 1, :] += acc * dt / 2
particles[:, 0, :] += particles[:, 1, :] * dt
acc = fn.forces(particles, marr)
particles[:, 1, :] += acc * dt / 2
x_and_v.append(particles.tolist())
time += dt
etot1 = fn.e_tot(particles, marr)
e_error = (etot1 - etot0) / etot0
return x_and_v, e_error
def leapfrog_drag(dt, tfinal):
particles, marr = fn.init_2body(0)
etot0 = fn.e_tot(particles, marr)
time = 0
while time < tfinal:
acc = fn.forces(particles, marr)[0]
particles[0, 1, :] += acc * dt / 2
particles[0, 0, :] += particles[0, 1, :] * dt
acc = fn.forces(particles, marr)[0]
particles[0, 1, :] += acc * dt / 2
grav = fn.forces(particles, marr)[1]
drag = fn.forces_migration(particles, marr)
acc = grav + drag
particles[1, 1, :] += acc * dt / 2
particles[1, 0, :] += particles[1, 1, :] * dt
grav = fn.forces(particles, marr)[1]
drag = fn.forces_migration(particles, marr)
acc = grav + drag * 1e1
particles[1, 1, :] += acc * dt / 2
eccentricity, semi_major_axis = fn.get_orbital_elements(
particles, marr)
eccentricity_save.append(eccentricity.tolist())
semi_major_axis_save.append(semi_major_axis.tolist())
x_and_v.append(particles.tolist())
time += dt
etot1 = fn.e_tot(particles, marr)
e_error = (etot1 - etot0) / etot0
return x_and_v, e_error, eccentricity_save, semi_major_axis_save