; UVWTFN
;---------------------------------------------------------------
;! Specify weighting function, Uniform or Natural
;# ADVERB UV IMAGING
;-----------------------------------------------------------------------
;;  Copyright (C) 1995, 2020
;;  Associated Universities, Inc. Washington DC, USA.
;;
;;  This program is free software; you can redistribute it and/or
;;  modify it under the terms of the GNU General Public License as
;;  published by the Free Software Foundation; either version 2 of
;;  the License, or (at your option) any later version.
;;
;;  This program is distributed in the hope that it will be useful,
;;  but WITHOUT ANY WARRANTY; without even the implied warranty of
;;  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;  GNU General Public License for more details.
;;
;;  You should have received a copy of the GNU General Public
;;  License along with this program; if not, write to the Free
;;  Software Foundation, Inc., 675 Massachusetts Ave, Cambridge,
;;  MA 02139, USA.
;;
;;  Correspondence concerning AIPS should be addressed as follows:
;;         Internet email: aipsmail@nrao.edu.
;;         Postal address: AIPS Project Office
;;                         National Radio Astronomy Observatory
;;                         520 Edgemont Road
;;                         Charlottesville, VA 22903-2475 USA
;-----------------------------------------------------------------------
;---------------------------------------------------------------
UVWTFN    LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC
----------------------------------------------------------------
UVWTFN
Type:  Adverb (String*2)
Use:   Specify weighting function used to equalize coverage of measured
       points in UV plane and otherwise adjust the weights.  It is a two
       character code.  If the first is 'N' then there is no correction
       to the data weights for the local density of samples or weights.
       If it is 'C', then the weights are corrected for the local
       density of samples (simple counts).  Otherwise, the weights are
       corrected for the local density of data weights (so-called
       uniform weighting).  The second character causes the weights to
       be modified before the local density of weights is measured and
       again before they are used.  If the second character is the
       letter 'V', the fourth root of the weights is taken; if it is 'S'
       the square root of the weights is taken; and if it is the
       letter 'O' all weights are taken as 1.0.
Null Value:  '  '
       Null value means Uniform weighting with no conversion of
       weights.
Procedures:
   CXPOLN........Procedure to make complex polarization images and beam.
   LINIMAGE......Build image cube from multi-IF data set.
   MAPPR.........Simplified access to IMAGR.
Tasks:
   IMAGR.........Wide-field and/or wide-frequency Cleaning / imaging task.
   PLAYR.........Task to load one or two images and play with them on the
                 TV.  UVWTFN is misused as FUNCTYPE for the 2nd image.
   SCIMG.........Full-featured imaging plus self-calibration loop with
                 editing.
   SCMAP.........Imaging plus self-calibration loop with editing.
   SDIMG.........Task to select and image random-position single-dish
                 data.
   UVMAP.........Makes images from calibrated UV data.
----------------------------------------------------------------