MEANCLIP
Name
     
       MEANCLIP
Purpose
     
       Computes an iteratively sigma-clipped mean on a data set
Explanation
     
       Clipping is done about median, but mean is returned.
      
       Called by SKYADJ_CUBE
Category
     
       Statistics
Calling Sequence
     
       MEANCLIP, Data, Mean, [ Sigma, SUBS =
              
              CLIPSIG=, MAXITER=, CONVERGE_NUM=, /VERBOSE, /DOUBLE ]
Input Positional Parameters
     
       Data:     Input data, any numeric array
      
       
Output Positional Parameters
     
       Mean:     N-sigma clipped mean.
      
       Sigma:    Standard deviation of remaining pixels.
Input Keyword Parameters
     
       CLIPSIG:  Number of sigma at which to clip.  Default=3
      
       MAXITER:  Ceiling on number of clipping iterations.  Default=5
      
       CONVERGE_NUM:  If the proportion of rejected pixels is less
          
           than this fraction, the iterations stop.  Default=0.02, i.e.,
          
           iteration stops if fewer than 2% of pixels excluded.
      
       /VERBOSE:  Set this flag to get messages.
      
       /DOUBLE - if set then perform all computations in double precision.
                
                 Otherwise double precision is used only if the input
                
                 data is double
Output Keyword Parameter
     
       SUBS:     Subscript array for pixels finally used.
Modification History
     
       Written by:     RSH, RITSS, 21 Oct 98
      
       20 Jan 99 - Added SUBS, fixed misplaced paren on float call, 
                  
                   improved doc.  RSH
      
       Nov 2005   Added /DOUBLE keyword, check if all pixels are removed  
                  
                  by clipping W. Landsman