totally incorrect calculation of matlab

I used quiver to plot a vector field. the code was :

 [x,y]=meshgrid(0:1:20);
 quiver(x,y,x^3-3*x*y,y^3-3*x^2*y)

However the results were completely different from expected, showing downward arrow at x=0, which should have been upward. Other arrows didn't match either.

Answer 1

[Mischa Kim]

Jaein, use instead

 [x,y] = meshgrid(0:1:20); 
 quiver(x,y,x.^3-3*x.*y,y.^3-3*x.^2.*y)   % note the dot-notation

Answer 2

[Jaein]

Thank uuuuuu