I can't draw the vector field

[x, y] = meshgrid(-0.9:0.3:0.9, -0.9:0.3:0.9);
R1 = (x.^2 + y.^2).^.5;
V = 1./R1;

figure(1)
surf(x, y, V)
view(-37.5, 20)

figure(2)
contour(x, y, V, 5)
hold on
axis square

[u, v] = gradient(V, 0.2);
quiver(x, y, -u, -v, 1.5)
axis equal

I can't draw the vector field. What's the problem

Answer 1

[Simon Chan]

The spacing used in function gradient is 0.2, but the spacing in your data is 0.3 and hence it give you an error. Try using same spacing.

Answer 2

[the cyclist]

The problem is the Inf values in u and v. Removing them:

[x, y] = meshgrid(-0.9:0.3:0.9, -0.9:0.3:0.9);
R1 = (x.^2 + y.^2).^.5;
V = 1./R1;
figure(1)
surf(x, y, V)
view(-37.5, 20)

figure
contour(x, y, V, 5)
hold on
axis square
[u, v] = gradient(V, 0.2);
u(isinf(u)) = NaN;
v(isinf(v)) = NaN;
quiver(x, y, -u, -v,1.5)
axis equal