astro/

potential_newton.pro

toppotential_newton

Astro

result = potential_newton(x, y, z, xpart, ypart, zpart, mass [, lengthunit=lengthunit] [, massunit=massunit] [, astro=astro] [, softening=softening] [, lomem=lomem])

Calculates the gravitational potential from a particle distribution at a list of positions.

Return value

This function returns the gravitational potential at each X,Y,Z position. If there are NPOS positions, Result is a vector of length NPOS.

Parameters

x in required: X coordinates at which to calculate potential.
y in required: Y coordinates at which to calculate potential.
z in required: Z coordinates at which to calculate potential.
xpart in required: X coordinates of particle positions defining the mass distribution.
ypart in required: Y coordinates of particle positions defining the mass distribution.
zpart in required: Z coordinates of particle positions defining the mass distribution.
mass in required: Mass of each particle.

Keywords

lengthunit in optional: Length unit, in cm (or kpc if /ASTRO is set). Default: 1kpc.
massunit in optional: Mass unit, in grams (or solar masses if /ASTRO is set). Default: 1 solar mass.
astro in optional: If /ASTRO is set then LENGTHUNIT and MASSUNIT are given in kpc and solar masses respectively, otherwise they are in CGS (Lengthunit in cm, Massunit in grams).
softening in optional: Plummer softening length. Default: 0 (no softening).
lomem in optional: If /LOMEM is set then sacrifice efficiency for lower memory usage

Examples

       Calculate the gravitational potential on a line along the x-axis from
       6 point masses placed at the vertices of a cube:

       xmasspos = [-1,-1,-1,-1,1,1,1,1]
       ymasspos = [-1,-1,1,1,-1,-1,1,1]
       zmasspos = [-1,1,-1,1,-1,1,-1,1]
       masses = REPLICATE(1.,8)
       xlinepos = 0.1*FINDGEN(20)
       ylinepos = REPLICATE(0.,20)
       zlinepos = REPLICATE(0.,20)
       potentials = POTENTIAL_NEWTON(xlinepos, ylinepos, zlinepos, xmasspos, ymasspos,
         zmasspos, masses)

Author information

History:

Written by: Jeremy Bailin 10 June 2008 Public release in JBIU

File attributes

Modifcation date:	Fri Jun 13 10:51:51 2008
Lines:	145

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