# Matrix arithmetic PHP Class During my studies in AI I wanted to solve the XOR problem; I wanted just to do a quick test so I started writing the code in PHP. Solving that problem I ended up to write a class that handles matrix operations as well.

Since there is no reason to use AI with PHP (I’ll explain this in another article) I share with you the class that handle the matrix operations.

In this article I’m going to show you some of the methods of the class Matrix and how to use them.
With this class you can sum or subtract two matrices, dot products or product by value, transpose and many other operations.
In the following examples is assumed that the file Matrix.php is included and the `Matrix` class is instantiated as `\$lib`:
`\$lib = new Matrix;`
As Numpy (a Python library), the matrix is an array of arrays; a matrix is defined as following:

``````include “Matrix.php"
\$lib = new Matrix;

// matrix 3×3
\$matrix = [
[1 , 2 , 3],
[4 , 5 , 6],
[7 , 8 , 9]
];

// matrix 3×1 with a row
\$matrix = [
[1 , 2 , 3]
];

// vector
\$vector = [
,
,

];

// scalar
\$scalar = [

];
// or more simply
\$scalar = 15;``````

#### Matrix Transpose

The method `matrixTranspose` returns the transpose of a matrix. Example:

``````\$matrix = [
[1 , 2],
[3 , 4]
];
\$matrix_transp = \$lib->matrixTranspose(\$matrix);
sm(\$matrix_transp); // it shows the matrix the result in a nice way``````

#### Dot product

The function `matrixDotProduct` has in input two matrices and it gives in output the dot product. If the two matrices are not compatible with each other an exception will be thrown.

``````\$m1 = [
[1 , 2 , 3],
[4 , 5 , 6]
];
\$m2 = [
[1 , 2],
[3 , 4],
[5 , 6]
];
\$result = \$lib->matrixDotProduct(\$m1,\$m2);
sm(\$result); // it shows the matrix the result in a nice way``````

#### RELU, SIGMOID, TANH, LOG operation

The method `matrixOperation` performs in each element of the given matrix the operation: RELU, SIGMOID, LOG (natural logarithm), NEGATIVE, TANH. In the following example we are going to perform SIGMOID to each element of `\$matrix`:

``````\$matrix = [
[1 , 2],
[4 , 5]
];
\$result = \$lib->matrixOperation('sigmoid’, \$matrix);
sm(\$result);

// This is what sm shows
// | 0.731 0.881 |
// | 0.982 0.993 |``````

#### Multiplie a matrix for a scalar value

The method `matrixTimesValue` multiplies a scalar value to all the elements of a given matrix. The first parameter is the matrix and the second is the number (or a matrix 1×1 dimension).

``````\$matrix = [
[1 , 2],
[4 , 5]
];
\$result = \$lib->matrixTimesValue(\$matrix, 10);

// Result of \$matrix * 10
// | 10 20 |
// | 40 50 |``````

The method `matrixSum` performs the addiction of two gives matrices as parameters.

``````\$m1 = [
[1 , 2],
[3 , 4]
];
\$m2 = [
[11 , 12],
[13 , 14]
];
\$result = \$lib->matrixSum(\$m1, \$m2);

// Result
// | 12 14 |
// | 16 18 |``````

#### Product value by value

This is a different from DOT product; it multiplies two matrices with same dimensions value by value _

``````\$m1 = [
[1 , 2],
[3 , 4]
];
\$m2 = [
[2 , 3],
[5 , 4]
];
\$result = \$lib->matrixProductValueByValue(\$m1, \$m2);

// Result
// | 2 6 |
// | 15 16 |``````

## Related Articles

### Brainy: a simple PHP class for machine learning

Category: resources

Brainy is a PHP class that helps you to create your neural network. I built Brainy just for fun during my artificial intelligence studies. If you are a web developer and you have just started ...

### Coming soon page

Category: resources

If you need a coming soon page, don't waste your time on developing it because you are going to use it for a short period. This coming soon page has a minimal design and it's made with PHP, HTML and ...

### Wordpress Empty Plugin

Category: resources

When I have to create a new Wordpress functionality I always use an empty plugin to start with. Here I'm going to explain how to develop your Wordpress plugin. If you are not interested in this ...

Category: PHP

Laravel Metadata is a lightweight PHP package that helps you to handle extra data on your models without adding any new fields on your database table. GitHub Repository PHP Packagist ...

### Fluent API PHP Class

Category: PHP

What is the fluent api? How to apply this design pattern in PHP? How to call a method both statically and not? Let's discover it!

### WP Social Importer

Category: tools

WP Social Importer is a wordpress plugin that imports news from Facebook, Instagram, Twitter into your website. This plugin transforms automatically the news from your social networks into wordpress ...