sdec

 SDEC N1 N2 N3 N4 HJD0 NFREQ FREQ1, FREQ2, ...  PFIX [PHASE1, ...] NPOLY -- 

                    Fits sinusoidal waves as function of HJD with the same fixed
                    frequencies at every wavelength. Option to fix phases too.

 If the phases are allowed to be free then five spectra are generated/period. 

    These are:
             (1) amplitude of cosine component, 
             (2) amplitude of sine component,
             (3) Total amplitude
             (4) Phase (in degrees) defined by 
                 Cos(omega*t+phi), phi = phase converted to degrees.
             (5) Total amplitude corrected for noise bias because a 
                 positive amplitude is always obtained even with no true 
                 signal present. The latter is set to zero if the power 
                 becomes < 0 during correction. 

  A character header item called 'Type' is set equal to 'Cosine', 'Sine', 
  'Amplitude', 'Phase' and 'Corr amplitude' for the various spectra. The 
  HJD0 and frequency used are stored in double precision items CSfreq and CSHJD

  If the phases are fixed then only the amplitude is fitted (Type = 'Amplitude')
  and the sequence of output spectra are just the amplitude spectra for each 
  frequency. The phase used is stored in the REAL header parameter CSphase

 Model fitted Y = A*COS(2*PI*PHI) + B*SIN(2*PI*PHI) for every period but a 
 polynomial is fitted and subtracted prior to computation to reduce power 
 leakage from low frequencies. Masked data are ignored and the fitted sinusoid
 is not subtracted from them.

 NB. This routine has to access the arrays in the wrong direction and may
     therefore page fault alot. 

 Parameters: 
     
  N1    -- Slot number of first spectrum to fit
  N2    -- Slot number of last spectrum to fit
  N3    -- Slot of first (cosine) component spectrum
  N4    -- Slot of first output spectrum with component subtracted (0 to
           ignore)
  HJD0  -- HJD0 of zero phase
  NFREQ -- Number of frequencies
  FREQ1, FREQ2, ... - Frequencies of waves. Enter as positive number if you want
                    it to be subtracted or negative if you don't (only
                    relevant if N4 is greater than 0). Units of days.
                    Units of cycles/day.
  PFIX   -- Fix phases? Y or N
  PHASE1, PHASE2, ... if FIX='Y' then you will need to fix the phases.
  NPOLY -- Number of coefficients of polynomial to subtract

This command belongs to the classes: time series , binary and fitting .