SIR against random generated [X,Y] position issue

My question is that the I need to plot random generated [x,y] positions against SIR(signal to interference ration), I used the meshgrid command for [x,y] and its returns a matrix but when I try to generate the surface plot an error occurs related of the dimensions of SIR, a vector of dimensions(100,1) as well as x and y originally.some times I do get a 3d surf plot but it look like an accordion instead of a Gaussian bell shape.

any help is appreciated kind regards Moises Salazar