title: Delta rule neural network teaching. Algorithm explanation necessary
body: <p>I'm doing a research, a project on neural networks. Just for myself. Earlier I've managed to understand a Backpropagation teaching algorithm, its basics, not the whole story, of course. But lots of resources refer to the delta rule, which is a bit special. I've already managed to understand that weights here are modified one by one. But there are a lot of questions. Could you explain me how does it work, but in more approachable way than it's on wikipedia. Just the algorithm, but with a clear explanation of steps and 'how it works'.</p>
  
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  <p>By the way, there are derivatives used for teaching. Can't understand why.
  And yes, no special source code is necessary unless it'll help.</p>