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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-

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
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

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

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Created by: m2h on:Thu Nov 17 15:23:05 1994