Welcome to the L3 Harris Geospatial documentation center. Here you will find reference guides and help documents.
﻿
>  Docs Center  >  Libraries  >  JBIU  >  FORCE_NEWTON

FORCE_NEWTON

## Name

FORCE_NEWTON

## Purpose

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

Astro

## Calling Sequence

Result = FORCE_NEWTON(X, Y, Z, Xpart, Ypart, Zpart, Mass)

## Inputs

X: X coordinates at which to calculate forces.
Y: Y coordinates at which to calculate forces.
Z: Z coordinates at which to calculate forces.
Xpart: X coordinates of particle positions defining the mass
distribution.
Ypart: Y coordinates of particle positions defining the mass
distribution.
Zpart: Z coordinates of particle positions defining the mass
distribution.
Mass: Mass of each particle.

## Keyword Parameters

LENGTHUNIT: Length unit, in cm (or kpc if /ASTRO is set). Default: 1kpc.
MASSUNIT: Mass unit, in grams (or solar masses if /ASTRO is
set). Default: 1 solar mass.
SOFTENING: Plummer softening length. Default: 0 (no softening).
ASTRO: 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).

## Outputs

This function returns the gravitational force at each X,Y,Z position.
If there are NPOS positions, Result is an NPOSx3 matrix.

## Example

Calculate the gravitational force 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)
forces = FORCE_NEWTON(xlinepos, ylinepos, zlinepos, xmasspos, ymasspos,
zmasspos, masses)

## Modification History

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

© 2019 Harris Geospatial Solutions, Inc. |  Legal