Neural Network Tutorial: Step-By-Step Guide for Beginners

In the field of machine learning, there are many interesting concepts. Here, in this neural networking tutorial, we’ll be discussing one of the fundamental concepts of neural networks. This article will help you in understanding the working of these networks by explaining the theory behind the same.

After finishing this artificial neural network tutorial, you’ll find out:

• What is a neural network?
• How does a neural network work?
• What are the types of neural networks?

What are Neural Networks?

A neural network is a system designed to act like a human brain. It’s pretty simple but prevalent in our day-to-day lives. 

A complex definition would be that a neural network is a computational model that has a network architecture. This architecture is made up of artificial neurons. This structure has specific parameters through which one can modify it for performing certain tasks.

Neural networks are also widely known as artificial neural networks (ANNs) or simulated neural networks (SNNs). 

This developing technology is a part of machine learning, a subset of artificial intelligence. The name of this technology is based on its resemblance to the human brain and how it tries to mimic the biological neuron signals we have.

They have extensive approximation properties. This means they can approximate a function to any level of accuracy irrespective of its dimension. Neural Networks find extensive applications in areas where traditional computers don’t fare too well. From Siri to Google Maps, neural networks are present in every place where Artificial Intelligence is used.

They are a vital part of artificial intelligence operations. Neural networks take inspiration from the human brain and so their structure is similar to one as well. 

How a Neural Network Works?

A neural network has many layers. Each layer performs a specific function, and the complex the network is, the more the layers are. That’s why a neural network is also called a multi-layer perceptron.

Before completely getting into the process of how neural networks work, you need to be familiar with the parts of it. The purest form of a neural network, which is also known as the node layer,  has three layers:

1. The input layer
2. The hidden layer
3. The output layer

As the names suggest, each of these layers has a specific purpose. These layers are made up of nodes. There can be multiple hidden layers in a neural network according to the requirements. The input layer picks up the input signals and transfers them to the next layer. It gathers the data from the outside world.  If you are familiar with the linear regression model, then it will be much easier for you to understand how does a neural network work, as each of the individual nodes can be compared to a unique linear regression model.

The hidden layer performs all the back-end tasks of calculation. A network can even have zero hidden layers. However, a neural network has at least one hidden layer. The output layer transmits the final result of the hidden layer’s calculation. 

Like other machine learning applications, you will have to train a neural network with some training data as well, before you provide it with a particular problem. But before we go more in-depth of how a neural network solves a problem, you should know about the working of perceptron layers first:

How do Perceptron Layers Work?

A neural network is made up of many perceptron layers; that’s why it has the name ‘multi-layer perceptron.’ These layers are also called hidden layers of dense layers. They are made up of many perceptron neutrons. They are the primary unit that works together to form a perceptron layer. These neurons receive information in the set of inputs. You combine these numerical inputs with a bias and a group of weights, which then produces a single output. 

For computation, each neuron considers weights and bias. Then, the combination function uses the weight and the bias to give an output (modified input). It works through the following equation:

combination = bias +weights * inputs

After this, the activation function produces the output with the following equation:

output = activation(combination)

This function determines what kind of role the neural network performs. They form the layers of the network. The following are the prevalent activation functions:

The Linear Function

In this function the output is only the combination of the neuron:

activation = combination

The hyperbolic Tangent Function

It is the most popular activation function among neural networks. It is a sigmoid function, and it lies between -1 and +1:

activation = tanh(combination)

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The Logistic Function

The logistic function is quite similar to the hyperbolic tangent function because it is a kind of sigmoid function, as well. However, it is different because it lies between 0 and 1:

activation = 11 + e-combination

The Rectified Linear Unit Function

Just like the hyperbolic tangent function, the rectified linear unit function is also prevalent. Another name for the rectified linear unit function is ReLU. ReLU is equal to the combination when it is equal to or greater than zero, and it’s negative if the combination is lower than (negative) zero. 

So, How Does a Neural Network Work Exactly?

Now that you know what is behind a neural network and how it works, we can focus on the working of a neural network. 

Here’s how it works:

1. Information is fed into the input layer which transfers it to the hidden layer
2. The interconnections between the two layers assign weights to each input randomly
3. A bias added to every input after weights are multiplied with them individually
4. The weighted sum is transferred to the activation function
5. The activation function determines which nodes it should fire for feature extraction
6. The model applies an application function to the output layer to deliver the output
7. Weights are adjusted, and the output is back-propagated to minimize error

The model uses a cost function to reduce the error rate. You will have to change the weights with different training models. 

1. The model compares the output with the original result
2. It repeats the process to improve accuracy

The model adjusts the weights in every iteration to enhance the accuracy of the output. 

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Types of Neural Networks

1) Recurrent Neural Network (RNN)

In this network, the output of a layer is saved and transferred back to the input. This way, the nodes of a particular layer remember some information about the past steps. The combination of the input layer is the product of the sum of weights and features. The recurrent neural network process begins in the hidden layers.

Here, each node remembers some of the information of its antecedent step. The model retains some information from each iteration, which it can use later. The system self-learns when its outcome is wrong. It then uses that information to increase the accuracy of its prediction in back-propagation. The most popular application of RNN is in text-to-speech technology. 

2) Convolutional Neural Network (CNN)

This network consists of one or multiple convolutional layers. The convolutional layer present in this network applies a convolutional function on the input before transferring it to the next layer. Due to this, the network has fewer parameters, but it becomes more profound. CNNs are widely used in natural language processing and image recognition. 

3) Radial Basis Function Neural Network (RBFNN)

This neural network uses a radial basis function. This function considers the distance of a point from the center. These networks consist of two layers. The hidden layer combines the features with the radial basis function and transfers the output to the next layer. 

The next layer performs the same while using the output of the previous layer. The radial basis function neural networks are used in power systems.

4) Feedforward Neural Network (FNN)

This is the purest form of an artificial neural network. In this network, data moves in one direction, i.e., from the input layer to the output layer. In this network, the output layer receives the sum of the products of the inputs and their weights. There’s no back-propagation in this neural network. These networks could have many or zero hidden layers. These are easier to maintain and find application in face recognition. 

5) Modular Neural Network

This network possesses several networks that function independently. They all perform specific tasks, but they do not interact with each other during the computation process.

This way, a modular neural network can perform a highly complex task with much higher efficiency. These networks are more challenging to maintain in comparison to simpler networks (such as FNN), but they also deliver faster results for complex tasks. 

What are the applications of neural networks? 

Now that you have got an in-depth understanding of how the neural network works, let us know about its applications. How the neural network works completely depends on how humans wish to implement it or assimilate it with some other technology, making it a revolutionary part of our lives. Here are a few instances!

1. Recognizing Characters:

With the help of neural networks, computers now can easily recognize handwriting. This falls under the umbrella of pattern recognition, where the computer can understand human handwriting, be it characters or numbers. 

Some of the sub-divisions such as Backpropagation neural networks, a multilayer neural network and Neocognitron are used for this technology.

Many software now has the facility of writing to text, where handwriting is converted to computer texts. All this is possible due to this technology.

2. Verifying signatures:

Signature verification is yet another popular application of neural networks. It is a non-vision-based technique. 

For this technology, the software is first trained with geometrical feature sets. The application then identifies these geometrical features or extracts features in the signature and confirms whether or not it is authentic.

This technology is a great way of avoiding fraud as it is far more accurate than a human. Therefore, the verification is highly reliable, swift and error-free.

3. Recognizing Human Face:

Human face detection is one of the most popular applications of neural networks where the software identifies the given face. After processing the image thoroughly, the software can classify which images have faces and which are faceless. 

For this technology, neural networks have to be well trained with algorithms. Some neural networks that are used for the training are full-connected multilayer feed-forward neural networks and PCA, which help reduce dimensionality and principal component analysis. This represents how does a neural network work in alignment with the advancing technology. 

4. Marketing and Sales

With the surge of e-commerce platforms, each of them is trying hard to improve the customer experience. They are doing everything from the website interface to suggesting items by analysing previous buying habits.

Neural networks enable the platforms to identify the customer’s choices and needs by analysing their search history, previous purchases and other browsing patterns. This is why when you search for something on Google or any such search engine, your wall or feed starts flooding with ads for similar items from these e-commerce platforms. 

By doing this, ANN has been revolutionary for marketers as they can now just simply take the help of software based on ANN and gather all the information required to make a perfect marketing campaign and attract the right crowds. 

5. Detecting Stock Market Trends

Neural networks are making their way in the stock market as well. In the stock market, they are used as a technical analysis tool. However, it is not like, with the help of neural network-based software, one will be able to hit the jackpot without knowing anything. 

In fact, neural networks do not make forecasts, but they analyse the prices and suggest to the user with best possible opportunities. Therefore, they help the user make data-driven decisions and not just follow their guts by analysing the prior patterns. They help the trader uncover aspects like non-linear interdependence and other sorts of patterns that other technical analysis processes might not help with. 

6. Building Artificial Assistance 

A neural network’s speech detection capability has helped build some of the greatest AI assistants of all time, like Alexa and Siri. the technology is still in its learning phase, where it may make mistakes in understanding certain languages and improper dialects. However, needless to say, that great progress has been made so far.

Particularly ANN is playing a vital role in this field, and some of the most used ones include Multilayer networks, multilayer networks with recurrent connections and Kohonen self-organizing feature maps. 

7. Healthcare 

In the field of healthcare, AI, more specifically, ANN, is gaining popularity in medical diagnosis. Its popularity is expected to grow in the future as evolving neural network technologies are considered to be ideal for detecting diseases using scans. 

Some of the examples of utilising deep-learning-based ANN models include timely diagnosing gastric cancer, which also with determining its sensitivity and specificity. By doing swift and accurate diagnoses, doctors can have more time in hand to aid the patient. 

8. Agriculture

Modern agriculture needs to be highly productive and efficient while maintaining the best quality. This not only applies to crops but also is for livestock production. Therefore, in order to meet these criteria, an advanced level of data analysis is becoming more and more crucial.

This is where neural networks come in handy, as ANNs are one of the most popular tools that combine the power of artificial intelligence to empower the agriculture industry to solve various repetitive, detail-oriented and time-taking tasks more efficiently. 

They are also broadly used in solving various classification and prediction tasks, with the help of which farmers can then make more precise decisions that will be in favour of the system. 

Best Books For Beginners in Neural Networks:

Even though this blog has covered most of the fundamentals of the neural network, if you wish to read more, you can check out these beginner-friendly books on neural networks. These books will give an in-depth understanding of how neural networks work.

Learn More About Neural Networks

That’s it in our neural network tutorial. You must’ve seen what a variety of tasks these networks can perform. They are used in almost all the technologies we use daily. If you want to find out more about neural networks, you can check our catalogue of courses on artificial intelligence and machine learning.

You can check our Executive PG Programme in Machine Learning & AI, which provides practical hands-on workshops, one-to-one industry mentor, 12 case studies and assignments, IIIT-B Alumni status, and more.