finding critical points in vector 2d vector field

Hello i have a mesh grid of x and y (range -2 to 2) and two vector u and v. I'm trying to detect critical points(saddle point) so i start by plotting the vectors using streamslice(x,y,u,v,10); (10 is the line density) but i'm still can detect the critical points.

[Star Strider]

Consider using the gradient and del2 functions to calculate the numerical derivatives and second derivatives of your data.