Neural Network Toolbox™

Link distance function

Syntax

• d = linkdist(pos)
  

Description

linkdist is a layer distance function used to find the distances between the layer's neurons given their positions.

linkdist(pos) takes one argument,

pos	N x S matrix of neuron positions

and returns the S x S matrix of distances.

Examples

Here you define a random matrix of positions for 10 neurons arranged in three-dimensional space and find their distances.

• pos = rand(3,10);
  D = linkdist(pos)
  

Network Use

You can create a standard network that uses linkdist as a distance function by calling newsom.

To change a network so that a layer's topology uses linkdist, set net.layers{i}.distanceFcn to 'linkdist'.

In either case, call sim to simulate the network with dist. See newsom for training and adaption examples.

Algorithm

The link distance D between two position vectors Pi and Pj from a set of S vectors is

• Dij = 0, if i == j
       = 1, if (sum((Pi-Pj).^2)).^0.5 is <= 1
       = 2, if k exists, Dik = Dkj = 1
       = 3, if k1, k2 exist, Dik1 = Dk1k2 = Dk2j = 1
       = N, if k1..kN exist, Dik1 = Dk1k2 = ...= DkNj = 1
       = S, if none of the above conditions apply
  

See Also

sim, dist, mandist

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