from scipy.integrate import odeint
from pylab import *  # for plotting commands

def deriv(x,t):  # return derivatives of the array y
    a = -2.0
    b = -0.1
    return array([ x[1], a*x[0]+b*x[1]])

time = linspace(0.0,100.0,1000)
xinit = array([0.0005,0.2])  # initial values
x = odeint(deriv,xinit,time)

figure()
plot(time,x[:,0])  # x[:,0] is the first column of x
xlabel('t')
ylabel('x')
show()

from scipy.integrate import odeint
from pylab import *  # for plotting commands

def deriv(z,t):  # return derivatives of the array y
    a = -0.1
    b = 0.2
    c = 0.1
    return array([z[1], a*z[2], z[3], b+c*z[1]])

time = linspace(0.0,10.0,1000)
zinit = array([0,0.2,0,0.1])  # initial values
z = odeint(deriv,zinit,time)

figure()
plot(time,z[:,0],label='x')  # z[:,0] is the first column of z
plot(time,z[:,2],label='y')  # z[:,2] is the third column of z
xlabel('t')
legend(loc='upper left')
show()