function [line,h,y,db]=test(M)

%hanning

if 0
j=0;
for n=0:1:M-1
    j=j+1;
    h(j)= (1- cos(  (2*pi*n)/(M-1)  )  )/2;
    if(n ~= (M-1)/2)
       h(j)= h(j).*( sin( 2*(n-((M-1)/2))) - sin(n-((M-1)/2)));
       h(j)= h(j)./(pi*(n-((M-1)/2)));
    end
end;
y=fft(h,512);
y=y/M;
j=0;
for n=0:1:255
    j=j+1;
    db(j)=20*log10(abs(y(j)));
 end;    
line=linspace(0,pi,256);
y=y(1:256);
end;

%hamming
if 0
j=0;
for n=0:1:M-1
    j=j+1;
    h(j)= (.54- .46*cos(  (2*pi*n)/(M-1))); 
    if(n ~= (M-1)/2)
       h(j)= h(j).*( sin( 2*(n-((M-1)/2))) - sin(n-((M-1)/2)));
       h(j)= h(j)./(pi*(n-((M-1)/2)));
    end
end;
y=fft(h,1024);
y=y/M;   % Normalize it
j=0;
for n=0:1:512
    j=j+1;
    db(j)=20*log10(abs(y(j)));
end;    
line=linspace(0,.5,512);
y=y(1:512);
end;


% rectangulare case 
if 0
j=0;
for n=0:1:M-1
    j=j+1;
    if ( n ~= 12)
      h(j)= (sin(2*n-(M-1)/2) - sin(n-(M-1)/2) )./(pi*(n-(M-1)/2));
    else 
      h(j)= h(j-1);
    end
end;
y=fft(h,512);
j=0;
for n=0:1:255
    j=j+1;
    db(j)=20*log10(abs(y(j)));
 end;    
y=y(1:256);
end;


%hamming BOOK page 586
if 1
j=0;
for n=0:1:M-1
    j=j+1;
    h1(j)= (.54- .46*cos(  (2*pi*n)/(M-1))); 
end;
j=0;
for n=0:1:M-1
   j=j+1; 
   if(n ~= (M-1)/2)
       temp= n- ((M-1)/2);
       h2(j)= (sin(.2*pi*temp))/(pi*temp);
    else
       h2(j)= h2(j-1);
    end
end

H1=fft(h1,256);
H2=fft(h2,256);
y=conv(H1,H2);
y=y/M;

%h= h1.*h2;

%t1=fft(h2,512);
%t1=t1(1:256);
%plot(linspace(0,.5,256),abs(t1));

%y=fft(h,1024);


for n=1:1:128
    db(n)=20*log10(abs(y(n)));
end;    
line=linspace(0,.5,128);
end;


%just the hamming window alone
if 0
j=0;
for n=0:1:M-1
    j=j+1;
    h(j)= (.54- .46*cos(  (2*pi*n)/(M-1))); 
end;
y=fft(h,1024);
y=y/M;
for n=1:1:512
    db(n)=20*log10(y(n));
end;    
line=linspace(0,.5,512);
end;

%just the hamming alone BOOK page 586
if 0
j=0;
for n=0:1:M-1
    j=j+1;
    h(j)= (.54- 0.46*cos(  (2*pi*n)/(M-1)) ); 
end;
y=fft(h,512);
y=y/M;
j=0;
for n=0:1:511
    j=j+1;
    db(j)=20*log10(abs(y(j)));
end;    
line=linspace(0,.5,256);
y=y(1:256);
db=db(1:256);
end;

%just the rectangulare window alone 
if 0
j=0;
for n=0:1:M-1
    j=j+1;
    h(j)=1;
end

y=fft(h,512);
y=y/M;

for n=1:1:256
    db(n)=20*log10(abs(y(n)));
end;    
line=linspace(0,.5,256);

end;


%rectangular  BOOK page 586
if 0
j=0;
for n=0:1:M-1
    j=j+1;
    if(n ~= (M-1)/2)
       h(j)= ( sin( .2*pi*(n-((M-1)/2)) ))./(pi*(n-((M-1)/2)));
    else
       h(j)= h(j-1);
    end;
end;
y=fft(h,512);
j=0;
for n=0:1:255
    j=j+1;
    db(j)=20*log10(abs(y(j)));
end;    
line=linspace(0,pi,256);
y=y(1:256);
end;