function [GX,GY]=gen_dgauss(sigma)

% laplacian of size sigma
%f_wid = 4 * floor(sigma);
%G = normpdf(-f_wid:f_wid,0,sigma);
%G = G' * G;
G = gen_gauss(sigma);
[GX,GY] = gradient(G); 

GX = GX * 2 ./ sum(sum(abs(GX)));
GY = GY * 2 ./ sum(sum(abs(GY)));
