Drawing field lines with MATLAB

[Minakami]

Homework Statement

Consider a uniformly charged half spherical shell. The total charge is Q and the radius is R.

a) Calculate the electric field as a function of z for – 5R < z < 5R.
b) Draw equipotential curves in the xz-plane for – 5R < x, z < 5R with at least 8 equallyspaced
curves.

Homework Equations

The Attempt at a Solution

I solved for the electric fields in the region z>R and z<R so part a) is done.
I'm trying to plot this field and the equipotential lines in MATLAB but I couldn't figure out how. I haven't really used MATLAB before but I think MATLAB can definitely do this.
I understand that the equipotential lines are perpendicular to the electric field lines. So maybe I can use this fact to draw the equipotential lines...

 

[viscousflow]

Investigate the function 'quiver3'. However, I am not sure if it accepts any other coordinate system other than cartesian.