%%
% vector field
% E(x,y,z)=[x-y y+x z]'
%
[x,y,z]=meshgrid(-4:1:4);
u=x-y;v=y+x;w=z;
quiver3(x,y,z,u,v,w)

xlabel('{\it x}','FontName','Times','FontSize',16)
ylabel('{\it y}','FontName','Times','FontSize',16)
zlabel('{\it z}','FontName','Times','FontSize',16)
text(-2.5,-5,4.5,'div {\it E} = 3, rot {\it E} = [0 0 2]^T',...
    'FontName','Times','FontSize',14)
% axis([-4.2 4.2 -4.2 4.2 -4.2 4.2])