The Perceptron

• The perceptron is a simple function that takes several inputs, multiplies each by a weight, sums them, and passes them through another function to give a single result.
• Summing just goes through the inputs and sums them.
• So, if the inputs are 3,5,-2 and 8, the sum 14.
• The function that the sum is passed through is called the transfer function.
• A simple function is a linear function, for example multiply by 2 or -0.3.
• If we take our sum, and pass it through the line we get 28 or -4.2.
• Another transfer function is the step function. If the sum is greater than the threshold, 1 is output, if not 0 is.
• So if the threshold is 7, our sum gives 1. If the threshold is 42, it gives 0. This is a lot like a McCullouch Pitts neuron with 1 being a spike, and 0 no spike. This is why MLPs are called (incorrectly in my view) neural nets.
• A third popular transfer function is the sigmoid function.
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• There are lots of other transfer functions.