MOMENTS(1)               TIPSY COMMANDS                 MOMENTS(1)



NAME
     moments - write the shape as a funtion of radius

SYNOPSIS
     moments box-number center-box-number particle  binning  bin-
     number filename minimum_radius

DESCRIPTION
     moments is a command that produces a file of name, filename,
     that contains various physical parameters that relate to the
     shape and orientation of the density distribution for parti-
     cles  of type particle in box, box-number. If the boxes box-
     number or center-box-number are not loaded an error is  gen-
     erated.   The  shapes  and orientations are calculated using
     the iterative technique described in  Katz  (Ap.J.  368:325,
     1991).  The initial guess for the center of the density dis-
     tribution is taken to be the center of mass of  box  center-
     box-number. The binning argument refers to how the particles
     are binned, either linearly or log  in  radius.   There  are
     bin-number  equal size bins distributed equally in radius or
     log radius between minimum_radius and the size of  box  box-
     number  depending  on the binning argument.  The output file
     has the following columns: radius,  b/a,  c/a,  phi,  theta,
     psi,  center-x,center-y,and center-z where b/a refers to the
     ratio between the intermediate axis and the  long  axis  and
     c/a  refers  to  the  ratio between the short and long axes.
     Phi, theta and psi refer to the Euler angles  that  describe
     the orientation of the density distribution.

OPTIONS
  Particle
     The possible choices for particle are:

          all
             Use the all the particles in box box-number

          dark
             Use only the dark matter particles in box box-number

          gas
             Use only the gas particles in box box-number

          star
             Use only the star particles in box box-number

  Binning
     The possible choices for binning are:

          lin
             Make  bin-number  bins  spaced  equally  in   radius
             between  minimum-radius  and  the  size  of box box-
             number



KQ Release 2.0     Last change: 22 MARCH 1994                   1






 MOMENTS(1)               TIPSY COMMANDS                 MOMENTS(1)



          log
             Make bin-number bins spaced equally  in  log  radius
             between  minimum-radius  and  the  size  of box box-
             number

SEE ALSO
      profile(1),  rotationcurve(1),

BUGS
     The technique doesn't always  converge,  particularily  when
     the  density  distribution  is very clumpy.  Things converge
     much better when the box center-box-number contains the true
     center for the density distribution in box box-number and is
     as small as possible.









































KQ Release 2.0     Last change: 22 MARCH 1994                   2