Mexican Hat Function
- There are various ways to move the points in the map in response
to input, but the Mexican Hat Function is the standard.
- The idea is that you find the closest point; that's the centre of
the hat.
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- You then find things around that target; that's the first circle, and
the body of the hat.
- You then find things even further out; that's the second circle.
- Things inside the first circle you move toward the target;
those in the second you move away.
- You follow the hat so that things closer to the centre move more in the
first circle.
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- Note the Y is the data point, and the Xs are the SOM units.
- Why is the centre of the hat not the data point?
