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

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