; INTERPOL
;---------------------------------------------------------------
;! specifies the type of averaging done on the complex gains
;# ADVERB CALIBRATION
;-----------------------------------------------------------------------
;;  Copyright (C) 1995, 2001, 2006, 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
;-----------------------------------------------------------------------
INTERPOL  LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC
----------------------------------------------------------------
INTERPOL
Type: Adverb  (String*4)
Use:  Standard data selection adverb; used to specify the
      interpolation function to be applied to the gain table:
      In CLCAL:
         '    ' = linear vector interpolation with no SN smoothing.
         '2PT ' = linear vector interpolation with no SN smoothing.
         'SELF' = do 2PT but only using SN entries from the same
                  source.  (New mode starting 20 April 2004.)
         'SELN' = Use only SN solution from same source which is
                  closest in time.  (This mode was called SELF before
                  20 April 2004.)
         'POLY' = Fit a polynomial to the SN rates and delays.  Use
                  the integral of the rate polynomial for the phases.
         'SIMP' = Simple linear phase connection between SN phase
                  entries, assumes phase difference less than 180 deg.
         'AMBG' = Linear phase connection using rates to resolve phase
                  ambiguities.
         'CUBE' = As AMBG but fit third order polynomial to phases and
                  rates.
      This adverb is only relevant when the data being operated
      on has an associated gain table.
Null value:  '    ' see above.
Tasks:
   CLCAL......Merges and smooths SN tables, applies them to CL tables.
Procedures: pass INTERPOL to CLCAL
   VLACLCAL...Runs CLCAL and prints the results with LISTR.
   VLBAFRGP...Fringe fit phase referenced data and apply calibration.
   VLBAFRNG...Fringe fit data and apply calibration.
   VLBAKRGP...Fringe fit phase referenced data and apply calibration.
   VLBAKRNG...Fringe fit data and apply calibration.
----------------------------------------------------------------