a=2;
del=a/10;

[X,Y]=meshgrid(0:del:a,0:del:a)
sin(X)

V=200*sin(X).*cos(Y)

contourf(X,Y,V)
%surf(X,Y,V)

[Ex,Ey]=gradient(-V,del,del)
Eabs=sqrt(Ex.^2+Ey.^2)
figure, surf(X,Y,Eabs)