annotate extra/genspecsines.m @ 13:844d341cf643 tip

Back up before ISMIR

function Y = genspecsines (ploc, pmag, pphase, N) 
% Compute a spectrum from a series of sine values 
% iploc, ipmag, ipphase: sine locations, magnitudes and phases, N: size of complex     
% spectrum; Y: generated complex spectrum of sines 
Y =zeros(N,1); % initialize output spectrum 
hN = N/2+1;                          % size of positive freq. spectrum 
for i=1:length(ploc);             % generate all sine spectral lobes 
  loc = ploc(i)-1;                      % location of peak (zero-based indexing),range ]0,hN-1[ 
  if (loc<=1||loc>=hN-1) continue; end; % avoid frequencies out of range 
  binremainder = round(loc)-loc; 
  lb = [binremainder-4:binremainder+4]'; % main lobe (real value) bins to read 
  lmag = genbh92lobe(lb)*10.^(pmag(i)/20); % lobe magnitudes of the complex exponential 
  b = 1+[round(loc)-4:round(loc)+4]';      % spectrum bins to fill (1-based indexing) 
  for m=1:9 
      if (b(m)<1)                          % peak lobe crosses DC bin 
          Y(2-b(m)) = Y(2-b(m)) + lmag(m)*exp(-1i*pphase(i)); 
      elseif (b(m)>hN)                     % peak lobe croses Nyquist bin 
          Y(2*hN-b(m)) = Y(2*hN-b(m)) + lmag(m)*exp(-1i*pphase(i)); 
      else                                 % peak lobe in positive freq. range 
          Y(b(m)) = Y(b(m)) + lmag(m)*exp(1i*pphase(i)) ... 
                    + lmag(m)*exp(-1i*pphase(i))*(b(m)==1||b(m)==hN); 
      end     
  end 
  Y(hN+1:end) = conj(Y(hN-1:-1:2));        % fill the rest of the spectrum 
end