If the function is continuous at the point you're interested in, it is sufficient to apply limit() to any 1-dimensional path approaching that point. E.g., to find the limit of
f(x,y)=x.^2+y.^2
as x,y-->0 you can take the 1-dimensional path x(t)=y(t)=t and reduce f to
f(x(t),y(t))=2*t.^2
Then, apply limit() to this 1D function of t as t-->0.
However, your example f=x^2/y is not continuous at x=y=0, so the limit is not defined there. Along x(t)=y(t)=t, the function approaches zero. Along the path x(t)=sqrt(t), y(t)=t the function converges to 1. Along the path x(t)=t, y(t)=t.^3 the function approaches Inf. If there is a particular path you know you are interested in, though, you could still apply limit() to that path.
