dt=0.0001
sigma=10
b=8.0/3.0

t1=[0]
x1=[1]
y1=[0]
z1=[0]
while t1[-1]<=51:
    x1.append(x1[-1]+(sigma*(y1[-1]-x1[-1]))*dt)
    y1.append(y1[-1]-(x1[-1]*z1[-1]-163.8*x1[-1]+y1[-1])*dt)
    z1.append(z1[-1]+(x1[-1]*y1[-1]-b*z1[-1])*dt)
    t1.append(t1[-1]+dt)

t=[0]
x=[1]
y=[0]
z=[0]
while t[-1]<=51:
    x.append(x[-1]+(sigma*(y[-1]-x[-1]))*dt)
    y.append(y[-1]-(x[-1]*z[-1]-150*x[-1]+y[-1])*dt)
    z.append(z[-1]+(x[-1]*y[-1]-b*z[-1])*dt)
    t.append(t[-1]+dt)

t2=[0]
x2=[1]
y2=[0]
z2=[0]
while t2[-1]<=51:
    x2.append(x2[-1]+(sigma*(y2[-1]-x2[-1]))*dt)
    y2.append(y2[-1]-(x2[-1]*z2[-1]-160*x2[-1]+y2[-1])*dt)
    z2.append(z2[-1]+(x2[-1]*y2[-1]-b*z2[-1])*dt)
    t2.append(t2[-1]+dt)

pl.figure(figsize=(15,8))
pl.plot(t,z,label="r=150",color="blue",linewidth=2)
pl.plot(t1,z1,label="r=163.8",color="green",linewidth=2)
pl.plot(t2,z2,label="r=160",color="red",linewidth=2)

pl.xlabel("time(s)")
pl.ylabel("z")
pl.title('Lorenz mode: z versus time')
pl.legend()
pl.show()

pl.figure(figsize=(15,8))
pl.plot(x,z,label="r=150",color="blue",linewidth=2)
pl.plot(x1,z1,label="r=163.8",color="green",linewidth=2)
pl.plot(x2,z2,label="r=160",color="red",linewidth=2)

pl.xlabel("x")
pl.ylabel("z")
pl.title('Phase space plot: z versus x')
pl.legend()
pl.show()