// 程序13-2
function [r, c] = Mexhat(A)
s = 3.0;
W = 4.0;
x = [- s*W : 1 : s*W];
D=double(A);
n = length(x);
h1 = fspecial1('log',115,3);
B1 = filter2(h1,A);
h2 = fspecial1('log',115,4);
B2 = filter2(h2,A);
B=abs(B1-(power(2,4))*B2);%B=B2-1/4*B1;1/4
radius=45;
thresh=100;
[r,c] = nonmaxsuppts(B, radius, thresh, D);