# Error with quiver: "unexpected vi type Nothing for quiver: nothing"

Greetings, everybody!
I’m having a problem using quiver from Plots.jl. As I understood, I have to provide 2 arrays that will state the initial coordinate of the vector, and other 2 that will state its final position. So I’m doing this:

``````using HypergeometricFunctions
using Plots

k(x,z) = -4*x*(1+x^2+z^2-2*x)^(-1)

f1(x,z) = (1+x^2+z^2-2*x)^(-3/2)*((1+x)*_₂F₁(1/2,1/2,1,k(x,z)) +
(x^2-z^2-1)*_₂F₁(3/2,3/2,2,k(x,z))/(1+x^2+z^2-2^x))

f2(x,z) = (1+x^2+z^2-2*x)^(-3/2)*(-2*z*_₂F₁(1/2,1/2,1,k(x,z))+
2*x*z*_₂F₁(3/2,3/2,2,k(x,z))/(1+x^2+z^2-2^x))

N = ceil(Int,(4/0.1+1)^2)
Ex = zeros(N)
Ez = zeros(N)
vx = zeros(N)
vz = zeros(N)

i=1
for x in -2:0.1:2
for z in -2:0.1:2
vx[i] = x
vz[i] = z
Ex[i] = (1/4*π)*f1(x,z)
Ez[i] = (1/4*π)*f2(x,z)
i+=1
end
end

quiver(vx,vz,quiver(Ex,Ez))
``````

Whith that I receive the following error message:

``````unexpected vi type Nothing for quiver: nothing
``````

Does anyone knows what is wrong?

You are missing an equal sign

``````quiver(vx,vz,quiver=(Ex,Ez))
``````

Though, `Ex` and `Ez` need to be the displacements from `vx` and `vy` and not the endpoints.