scargle

         Compute the lomb-scargle periodogram of an unevenly sampled
         lightcurve

         time series analysis

   scargle,t,c,om,px,fmin=fmin,fmax=fmax,numf=numf,pmin=pmin,pmax=pmax,
            nu=nu,period=period,omega=omega,fap=fap,signi=signi

         time: The times at which the time series was measured
         rate: the corresponding count rates

         fmin,fmax: minimum and maximum frequency (NOT ANGULAR FREQ!)
                to be used (has precedence over pmin,pmax)
         pmin,pmax: minimum and maximum PERIOD to be used
         omega: angular frequencies for which the PSD values are
                desired
         fap : false alarm probability desired
               (see Scargle et al., p. 840, and signi
               keyword). Default equal to 0.01 (99% significance)
         noise: for the normalization of the periodogram and the
            compute of the white noise simulations. If not set, equal to
            the variance of the original lc.
         multiple: number of white  noise simulations for the FAP
            power level. Default equal to 0 (i.e., no simulations).
         numf: number of independent frequencies

         old : if set computing the periodogram according to J.D.Scargle
            1982, ApJ 263, 835. If not set, computing the periodogram
            with the fast algorithm of W.H. Press and G.B. Rybicki,
            1989, ApJ 338, 277.
         debug: print out debugging information if set
         slow: if set, a much slower but less memory intensive way to
            perform the white noise simulations is used.

            om   : angular frequency of PSD
            psd  : the psd-values corresponding to omega

            nu    : normal frequency  (nu=omega/(2*!DPI))
            period: period corresponding to each omega
            signi : power threshold corresponding to the given
                    false alarm probabilities fap and according to the
                    desired number of independent frequencies
            simsigni : power threshold corresponding to the given
                    false alarm probabilities fap according to white
                    noise simulations
            psdpeaksort : array with the maximum peak pro each simulation

         The Lomb Scargle PSD is computed according to the
         definitions given by Scargle, 1982, ApJ, 263, 835, and Horne
         and Baliunas, 1986, MNRAS, 302, 757. Beware of patterns and
         clustered data points as the Horne results break down in
         this case! Read and understand the papers and this
         code before using it! For the fast algorithm read W.H. Press
         and G.B. Rybicki 1989, ApJ 338, 277.
         The code is still stupid in the sense that it wants normal
         frequencies, but returns angular frequency...

          Version 1.0, 1997, Joern Wilms IAAT
          Version 1.1, 1998.09.23, JW: Do not normalize if variance is 0
             (for computation of LSP of window function...)
          Version 1.2, 1999.01.07, JW: force numf to be int
          Version 1.3, 1999.08.05, JW: added omega keyword
          Version 1.4, 1999.08
              KP: significance levels
              JW: pmin,pmax keywords
          Version 1.5, 1999.08.27, JW: compute the significance levels
               from the horne number of independent frequencies, and not from
               numf
          Version 1.6, 2000.07.27, SS and SB: added fast algorithm and FAP
               according to white noise lc simulations.
          Version 1.7, 2000.07.28 JW: added debug keyword, sped up
               simulations by factor of four (use /slow to get old
               behavior of the simulations)

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