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# poten_slow.pro

## toppoten_slow

`result = poten_slow(pos, mass)`

This function computes the potential energy of a mass distribution. It directly sums the interactions between all particles, so it is exact (to within machine precision) but scales as N^2. The poten_tree routine is slightly (1%) less accurate, but scales as NlogN. This routine is faster for <<10^4 particles, because the algorithm is simpler. Furthermore, this routine can calculate the potential in any dimension, whereas poten_tree is restricted to 3 dimensions.

### Return value

The potential energy of the system. It is assumed that G=1, so that PE = sum_i (sum j > i (m_i * m_j / r_ij) )

### Parameters

- pos in required
A [ndim, n] array of n-dimensional particle locations

- mass in required
A n element vector of masses

## File attributes

Modifcation date: | Mon Jul 12 19:53:21 2010 |

Lines: | 50 |