Program:      RADPROF

Purpose:      Solves the radial surface density distribution from a strip
              integral of the brightness distribution. USE PROGRAM
              RADIAL AS FRONT END FOR RADPROF.


Category:     ANALYSIS, FITTING, PROFILES, RADIO

File:         radprof.shl

Author:       M.G.R. Vogelaar
              (Initial code: Myung-Hyun Rhee, Rob Swaters)

Keywords:     See radial.dc1

   PA=        Position angle (deg) of galaxy:

   INCL=      Inclination (deg) of galaxy:
              Inclination of 90.0 degrees not allowed.

   GUESS=     Enter initial estimate:                            [L]

              Enter one of: L = Linear Regression
                            E = Exponential Decreasing
                            G = Gaussian Distribution
                            F = Flat Distribution

 **IDENT=     Give integer to identify output:                   [0]

   SCF=       Give scale factor for density:                     [1]


   SIGMA=     Give noise in your data points:                    [1]

   ITMAX=     Maximum number of iterations:                     [10]

   BEAM=      Half power beam width (arcsec):                  [0.0]

   POS=       Positions of data points (arcsec):
              First position must be zero and positions must be
              equally spaced.

   EAST=      Values at east side:

   WEST=      Values at west side:

   TABLEFILE= Enter output filename for densities:      [RADIAL.DAT]
              This file contains the observed and fitted 
              integrated flux for east, west and the average profile,
              and the fitted surface densities.
              


Description:  RADPROF solves the radial surface density distribution from
              a strip integral of the brightness distribution of a galaxy.
              The method is simular to the one decribed by Lucy,
              (The Astronomical Journal, Vol. 79, Number 6, June 1974).
              The geometry of the problem is determined by the inclination
              and the position angle of the galaxy together with the position
              angle of the resolution axis of the strip integral.
              The method of Lucy takes care of the existence of noise
              in the data and used an iterative scheme to take that into
              account.

Algorithm:    1. read in the observational data of observation 1
                 from the data file for both the east and west side
              2. convert the positions on the resolution (=position)
                 axis to radial distances in the plane of the galaxy
              3. make an inital guess of the radial distribution
              4. start lucy iterative scheme to compute the true
                 radial distribution
              5. print and plot the results of the observation

              Array's
              R (input)  distance to centre along the resolution axis
              R (out) distance in the plane of the galaxy
              V (out) radial distr. east and west (solar masses/pc**2)
              S (out) radial distr. east and west (cumulative perc.)
              T (out) average radial distr. (solar masses/pc**2)
              U (out) average radial distr. (cum. perc.)


              This program is usually started by program RADIAL which
              serves as a front-end to RADPROF.
              For a further description of the method see:
              Warmels, R.H., 1988b, A&AS 72, 427

Updates:      Jul 30, 1999: VOG, Document created.