# Adding arrows in vector fields

I'm using plot_vector_field3d, and I'm not getting any arrows at the ends of the vectors. The documentation seems to indicate this would be automatic. Is there something I'm missing?

Could you please provide an example with missing arrows ?

Here's the full code

x,y,z,r,delta = var('x','y','z','r','delta')

epsilon = 400 delta = epsilon/400

h=spline([(0,0),(delta,1),(delta/2,1/2),(delta/4,1/8),(3

delta/4,7/8),(delta/100,0),(99delta/100,1)])def f(r): if r >=0 and r <=2

delta: return 1 elif r>=2delta and r<= 3delta: return h(3delta-r) elif r>=3delta and r<=4delta: return 0def g(z): if z >=0 and z <= delta: return 0 elif z >= delta and z<=2

delta: return h(z-delta) elif z>=2delta and z<=3delta: return h(3delta-z) elif z>=3delta and z<=4delta: return (-1)h(abs(3delta-z)) elif z>=4delta and z<=5delta: return (-1)h(abs(z-5delta)) elif z>=5delta and z<=6delta ...(more)