[X1,X2]=meshgrid([0.001:0.001:0.035],[0.001:0.001:0.025]);
[n,m]=size(X1);

for i=1:n
   for j=1:m
      S(i,j)=extrat([X1(i,j) X2(i,j)]);
   end
end
%figure; mesh(X1,X2,-S);
%figure; contour(X1,X2,-S,[0 5 10 15 18]);

[xo,So,nS] = complex('extrat',[0.019 0.018],1,[0.001 0.001],[0.03 0.03],[],[],[],0.005)
