Matrix

Stand-alone Linear Algebra Library for PHP

Installation

Include this in your composer.json and then run composer install:

"mcordingley/linearalgebra": "0.9.*"

Usage

Start with a use statement for the class:

use \mcordingley\LinearAlgebra\Matrix;

Then, instantiate a new instance of the matrix class like so:

$matrix = new Matrix([
    [0, 1, 2],
    [3, 4, 5],
    [6, 7, 8]
]);

You can also generate an identity matrix with the identity factory function:

$threeByThreeIdentityMatrix = Matrix::identity(3);

With the matrix instance, you can retrieve individual elements with get using the zero-based indices of the row and column that you want:

$element = $matrix->get($row, $column);

It's also possible to find out how large the matrix is with the rows and columns properties:

$rows = $matrix->rows;
$columns = $matrix->columns;

You can also add, subtract, and multiply the matrix with scalar values and other matrices. All operations return a new Matrix and do not modify the underlying matrix:

$addedScalar = $matrix->add(3);
$addedMatrix = $matrix->add($anotherMatrix);
$subtractedScalar = $matrix->subtract(2);
$subtractedMatrix = $matrix->subtract($anotherMatrix);
$multipliedByScalar = $matrix->multiply(4);
$multipliedByMatrix = $matrix->multiply($anotherMatrix);

Matrices can be compared with equals to see if they're equal:

if ($matrix1->equals($matrix2)) {
    // Equality for all!
}

In addition to these basic operations, the Matrix class offers other common matrix operations:

$matrix->inverse()
$matrix->adjoint()
$matrix->determinant()
$matrix->trace()
$matrix->transpose()
$matrix->submatrix()

It's also possible to run a map over the matrix:

$squaredElements = $matrix->map(function($element, $row, $column, $matrix) {
    return $element * $element
});

Change-log

• 0.9.0

  • Bump version up to represent that this is close to it's final form.
  • Merged PR for faster inverse calculations
  • KISS Vector class good-bye.
  • Renamed eq to equals.
  • Removed set function, so instantiated objects are immutable.

• 0.3.0

  • Added the identity factory function
  • Using Cholesky decomposition for faster matrix inversions for applicable matrices
  • Added eq function to test equality of matrices
  • Implemented the ArrayAccess interface

• 0.2.0

  • Created the Vector type
  • \MCordingley namespace is now \mcordingley
  • Matrix functions that return a new Matrix now return a new instance of the called class

• 0.1.0

  • Created the Matrix type
  • Scalar Addition
  • Scalar Subtraction
  • Scalar Multiplication
  • Matrix Addition
  • Matrix Subtraction
  • Matrix Multiplication
  • Inverse
  • Adjoint
  • Determinant
  • Trace
  • Transpose
  • Submatrix
  • Map