September 2017
Beginner to intermediate
270 pages
5h 53m
English
Content preview from Neural Networks with R
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Sigmoid
The sigmoid function is a mathematical function that produces a sigmoidal curve; a characteristic curve for its S shape. This is the earliest and often used activation function. This squashes the input to any value between 0 and 1, and makes the model logistic in nature. This function refers to a special case of logistic function defined by the following formula:
In the following figure is shown a sigmoid curve with an S shape: