Program:       RADIAL

Purpose:       Derive radial surface density distribution from a 2-dim 
               total HI map using the 'Lucy method'.

Category:      ANALYSIS, FITTING, PROFILES, RADIO

File:          radial.c

Author:        M.G.R. Vogelaar
               (radprof.f by Rob Swaters)

Keywords:

   INSET=      Give set, subsets:
               Maximum number of subsets is 1.

   POSANG=     Enter position angle major axis:                   [0.0]

   OUTPOS=     Enter rotation center in grids:                [0.0 0.0] 
   
   BOX=        Give box in .....                        [entire subset]
               Enter a box for the rotated set 
               (see description)

   TABLEFILE=  Enter output filename for densities:        [RADIAL.DAT]
   
   GUESS=      Enter initial estimate:                              [L]

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

   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]
  
   GRDEVICE=   Plot device:                           [List of devices]
               Destination of plot, Screen or Hardcopy.


Description:   For edge on or highly inclined galaxies a radial surface 
               density distribution can be obtained by this program. it uses
               the method described in Warmels, R.H., 1988b, A&AS 72, 427
               The core of the method is based on the 'Lucy method'
               (The Astronomical Journal, Vol. 79, Number 6, June 1974)
               and it is written as a separate task called RADPROF which
               is called by RADIAL as if it is a subroutine. 
               You can use RADPROF independently but then you need
               to do the extra work which RADIAL does for you.

               RADIAL starts with 2-dim total HI set (INSET=) and uses data
               within user given limits (BOX=).
               It asks to enter a value for the angle (deg.) of the 
               major axis wrt. the north in POSANG=.
               RADIAL then rotates your set so that its major axis is 
               parallel to the direction of the east by calling task
               REPROJ. The rotation center is entered in OUTPOS=.
               The rotated output is stored in 'tempREPROJsetxxxxx' 
               and displayed in GIDS. Now it is rotated, its data can be 
               summed in the y-direction and the results of this process
               are written in two ASCII files on disk called radialEAST.dat
               and radialWEST.dat for both the east and west parts of the 
               (rotated) galaxy. These files are the basic input files for 
               the iterative Lucy method.
               
               Now RADPROF is called (deputied). It asks you to 
               enter a file name to store its results (strip distributions
               and surface densities as function of radius as a result
               of Lucy"s iterative solution scheme for a radial HI
               distribution). The method needs an initial estimate for
               the distribution. This is one of the following:
               L = Linear Regression
               E = Exponential Decreasing
               G = Gaussian Distribution
               F = Flat Distribution  
               The abbreviation is used in keyword GUESS=
               Further a scale factor is asked in SCF=,
               the noise in the data points in SIGMA=
               and the maximum number of iterations in ITMAX=
               Also the Full Width at Half Maximum is needed (BEAM=).
               This is a value in seconds of arc.
               Then the iteration starts and the results are written to 
               file and to a plot on the device that you selected in
               GRDEVICE=


Related doc:   radprof.dc1, radprof.f        


Notes:         RADIAL can only work together with RADPROF.

Example:       Example of used keywords and filenames:

               INSET= rob param 0
               POSANG= 57
               OUTPOS= -4.22 -4.96
               BOX= -41 -25 39 22                
               TABLEFILE=               
               GUESS=
               SCF= 
               SIGMA= 3
               ITMAX=
               BEAM= 3
               GRDEVICE= x11             
              
Updates:       Jul 30, 1999: VOG, Document created.