Book Image

Deep Learning from the Basics

By : Koki Saitoh
5 (1)
Book Image

Deep Learning from the Basics

5 (1)
By: Koki Saitoh

Overview of this book

Deep learning is rapidly becoming the most preferred way of solving data problems. This is thanks, in part, to its huge variety of mathematical algorithms and their ability to find patterns that are otherwise invisible to us. Deep Learning from the Basics begins with a fast-paced introduction to deep learning with Python, its definition, characteristics, and applications. You’ll learn how to use the Python interpreter and the script files in your applications, and utilize NumPy and Matplotlib in your deep learning models. As you progress through the book, you’ll discover backpropagation—an efficient way to calculate the gradients of weight parameters—and study multilayer perceptrons and their limitations, before, finally, implementing a three-layer neural network and calculating multidimensional arrays. By the end of the book, you’ll have the knowledge to apply the relevant technologies in deep learning.
Table of Contents (11 chapters)

Activation Function

The activation function represented by equation (3.3) changes output values at a threshold and is called a "step function" or a "staircase function." Therefore, we can say, "a perceptron uses a step function as the activation function." In other words, a perceptron chooses a "step function" as the activation function from many candidate functions. When a perceptron uses a step function as the activation function, what happens if a function other than a step function is used as the activation function? Well, by changing the activation function from a step function to another function, we can move to the world of a neural network. The next section will introduce an activation function for a neural network.

Sigmoid Function

One of the activation functions often used in neural networks is the sigmoid function, represented by equation (3.6):

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