help L1AR

  function [omega,mag,phi,a,sigma]=L1AR(y,freqNum,ARorder,freqrange,N)
  input
               y: observation record signal+noise
         freqNum: number of signals
         ARorder: order of autoregressive filter (default value 0)
       freqrange: interested frequency interval (default value [0 pi])
               N: resolution=2*pi/N (default value 2*length(y))
  output
           vopt:
          omega:  estimated frequencies of signals
            mag:  magnitudes of signals
            phi:  estimated phase angles
              a:  coefficients of AR filter
          sigma:  whitened noise variance