'Display the coil in the 3D view.
If half is True, display only one half of the coil.'

def display(self, half=False):

    (n, l, m) = self.base_vectors()
    theta = np.linspace(0, ((2 - half) * np.pi), 30)
    theta = theta[..., np.newaxis]
    coil = (self.radius * ((np.sin(theta) * l) + (np.cos(theta) * m)))
    coil += self.position
    (coil_x, coil_y, coil_z) = coil.T
    if (self.plot is None):
        self.plot = self.app.scene.mlab.plot3d(coil_x, coil_y, coil_z, tube_radius=0.007, color=(0, 0, 1), name=self.name)
    else:
        self.plot.mlab_source.set(x=coil_x, y=coil_y, z=coil_z)
