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POTENTIAL_NEWTON

POTENTIAL_NEWTON

Name


      POTENTIAL_NEWTON

Purpose


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

Category


      Astro

Calling Sequence


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

Inputs


      X: X coordinates at which to calculate potential.
      Y: Y coordinates at which to calculate potential.
      Z: Z coordinates at which to calculate potential.
      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).
      LOMEM: If /LOMEM is set then sacrifice efficiency for
                  lower memory usage

Outputs


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

Example


      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)

Modification History


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



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