ARTICLE: Neural Networks - Backpropagation
- Marco Singh
- 30. sep. 2016
- 1 min læsning
When I was first introduced to neural networks I found it hard to obtain a detailed description of the innner workings of the backpropagation algorithm. The backpropagation algorithm, which is the algorithm that actually makes the neural network capable of learning, is so essential that I wanted to know every single detail of the derivation (that's just how I am as a person!). This is thus what I am trying to achieve with this paper. Before diving into the derivations of the backpropagation algorithm, I will recap how the feedforward network is calculated such that a reader easily can understand the mathematical derivations and the chosen notation. After having derived the general backpropgation result, I will use a specific choice of cost function (the quadratic cost function) and a specific activation function (the sigmoid function) to obtain the backpropagation for these specific choices. The reader will then easily be able to use another choice of cost function and/or activation function. Lastly, I will show the backpropagation results when regularization is used. Concretely I will use the backpropagation when using L1 or L2 regularization.
This paper requires prior knowledge of a simple neural network, but briefly recaps the forward propagation algorithm to calculate the network prediction from initial input data.
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