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%  exa040501e.m,  for  example 4.5.1 and fig 4.5.1(e) 
%  核函数的等高线图 
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clear; 
 
sigma=1.5; 
fs=1/128; 
for t=1:128; 
   for f=1:128; 
      tt=(t-64)*(t-64); 
      f1=(f-64)/128; 
      ff=f1*f1; 
   g(t,f)=exp(-tt*ff/sigma); 
end 
end 
t=-63:64; 
f=-0.5+fs:fs:.5; 
 
subplot(211) 
contour(t,f,g,1,'b');grid;