from Power Spectrum Estimation (non-parameteric methods) by payam masoumi
there is a simple demo for non parameteric spectral estimation methods

sinusoid(x)
function temp = sinusoid(x)

global sigtype;
global freq;
global amp;
global vari;

sigtype = 2;
HH = findobj(gcf,'Tag','sin_freq1');
p = str2num(get(HH,'String'));
if ~p
    freq(1)=0;
else
    freq(1)=p;
end;

HH = findobj(gcf,'Tag','sin_amp1');
p = str2num(get(HH,'String'));
if ~p
    amp(1)=0;
else
    amp(1)=p;
end;

HH = findobj(gcf,'Tag','sin_freq2');
p = str2num(get(HH,'String'));
if ~p
    freq(2)=0;
else
    freq(2)=p;
end;

HH = findobj(gcf,'Tag','sin_amp2');
p = str2num(get(HH,'String'));
if ~p
    amp(2)=0;
else
    amp(2)=p;
end;

HH = findobj(gcf,'Tag','sin_var');
p = str2num(get(HH,'String'));
if ~p
    vari=0;
else
   vari=p;
end;

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