IRAF Help page for: GAPFILL


GAPFILL (Jan93)               grasp.grtools              GAPFILL (Jan93)



NAME
    gapfill  --  Fill  gaps  in  GONG  time  series  via  autoregressive 
    interpolation.
    
    
USAGE
    gapfill input output maxlen fill_factor
    
    
PARAMETERS
    
    input
        Input time series image list.
    
    output
        Output gap-filled time series image list.
    
    maxlen
        Maximum Auto-regressive filter length.
    
    fill_factor
        Filling factor.
    
    
DESCRIPTION
    
    GAPFILL  uses  a  simplified  autoregressive technique to fill short
    gaps in the GONG time series.  The positions of good  data  segments
    are  determined from the window funtion contained in the last row of
    the input time series images.
    
    The maximum AR filter length to be used is given  by  maxlen.   Gaps
    will  not  be  filled  unless  their length is less than fill_factor
    times the smaller of maxlen and the number of points in the  largest
    good segment adjacent to the gap.
    
    The  subroutine used was written by Tim Brown (HAO) and is described
    in the paper "A Technique for Estimating Complicated  Power  Spectra
    From Time Series with Gaps", Ap.J., 349, 667, 1990.
    
    
EXAMPLES
    
    1. To gap fill a GONG time series:
    
      gr> gapfill tcvdt921124d250 gftcvdt921124d250
    
    
TIME REQUIREMENTS
    
    
BUGS
    
    
SEE ALSO

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