Solving the Lorenz System

lorrenz.py

def lorenz(x0,y0,z0,start_time,time_step):
    """
    Returns an array of points, which the lorenz system passes by iteratively perfoming each rk4 timestep
    """
    x,y,z = [x0],[y0],[z0] # Start Points
    count = 0
    t = start_time or 0 # Start Time
    dt = time_step or 0.01 # Time Step
    while t < 150:
        t+= dt
        tempx,tempy,tempz = x[count],y[count],z[count] # Temporary Start Points
        func = np.array([dx,dy,dz])
        runge_kutta_4 = rk4(func,t,tempx,tempy,tempz,dt) # Rk4 Function
        tempx += runge_kutta_4[0]
        tempy += runge_kutta_4[1]
        tempz += runge_kutta_4[2]
        count +=1
        x.append(tempx)
        y.append(tempy)
        z.append(tempz)
    return x,y,z