Matrix.php

<?php
 
/*
 *
 *  ____            _        _   __  __ _                  __  __ ____
 * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
 * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
 * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
 * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * @author PocketMine Team
 * @link http://www.pocketmine.net/
 *
 *
*/
 
declare(strict_types=1);
 
namespace pocketmine\math;
 
use function implode;
use function max;
use function substr;
 
class Matrix implements \ArrayAccess{
    private array $matrix = [];
    private int $rows;
    private int $columns;
 
    public function offsetExists($offset) : bool{
        return isset($this->matrix[(int) $offset]);
    }
 
    #[\ReturnTypeWillChange]
    public function offsetGet($offset){
        return $this->matrix[(int) $offset];
    }
 
    public function offsetSet($offset, $value) : void{
        $this->matrix[(int) $offset] = $value;
    }
 
    public function offsetUnset($offset) : void{
        unset($this->matrix[(int) $offset]);
    }
 
    public function __construct(int $rows, int $columns, array $set = []){
        $this->rows = max(1, $rows);
        $this->columns = max(1, $columns);
        $this->set($set);
    }
 
    public function set(array $m) : void{
        for($r = 0; $r < $this->rows; ++$r){
            $this->matrix[$r] = [];
            for($c = 0; $c < $this->columns; ++$c){
                $this->matrix[$r][$c] = $m[$r][$c] ?? 0;
            }
        }
    }
 
    public function getRows() : int{
        return $this->rows;
    }
 
    public function getColumns() : int{
        return $this->columns;
    }
 
    public function setElement(int $row, int $column, float $value) : void{
        if($row > $this->rows or $row < 0 or $column > $this->columns or $column < 0){
            throw new \InvalidArgumentException("Row or column out of bounds (have $this->rows rows $this->columns columns)");
        }
        $this->matrix[$row][$column] = $value;
    }
 
    public function getElement(int $row, int $column) : float{
        if($row > $this->rows or $row < 0 or $column > $this->columns or $column < 0){
            throw new \InvalidArgumentException("Row or column out of bounds (have $this->rows rows $this->columns columns)");
        }
 
        return $this->matrix[$row][$column];
    }
 
    public function isSquare() : bool{
        return $this->rows === $this->columns;
    }
 
    public function add(Matrix $matrix) : Matrix{
        if($this->rows !== $matrix->getRows() or $this->columns !== $matrix->getColumns()){
            throw new \InvalidArgumentException("Matrix does not have the same number of rows and/or columns");
        }
        $result = new Matrix($this->rows, $this->columns);
        for($r = 0; $r < $this->rows; ++$r){
            for($c = 0; $c < $this->columns; ++$c){
                $element = $matrix->getElement($r, $c);
                $result->setElement($r, $c, $this->matrix[$r][$c] + $element);
            }
        }
 
        return $result;
    }
 
    public function subtract(Matrix $matrix) : Matrix{
        if($this->rows !== $matrix->getRows() or $this->columns !== $matrix->getColumns()){
            throw new \InvalidArgumentException("Matrix does not have the same number of rows and/or columns");
        }
        $result = clone $this;
        for($r = 0; $r < $this->rows; ++$r){
            for($c = 0; $c < $this->columns; ++$c){
                $element = $matrix->getElement($r, $c);
                $result->setElement($r, $c, $this->matrix[$r][$c] - $element);
            }
        }
 
        return $result;
    }
 
    public function multiplyScalar(float $number) : Matrix{
        $result = clone $this;
        for($r = 0; $r < $this->rows; ++$r){
            for($c = 0; $c < $this->columns; ++$c){
                $result->setElement($r, $c, $this->matrix[$r][$c] * $number);
            }
        }
 
        return $result;
    }
 
    public function divideScalar(float $number) : Matrix{
        $result = clone $this;
        for($r = 0; $r < $this->rows; ++$r){
            for($c = 0; $c < $this->columns; ++$c){
                $result->setElement($r, $c, $this->matrix[$r][$c] / $number);
            }
        }
 
        return $result;
    }
 
    public function transpose() : Matrix{
        $result = new Matrix($this->columns, $this->rows);
        for($r = 0; $r < $this->rows; ++$r){
            for($c = 0; $c < $this->columns; ++$c){
                $result->setElement($c, $r, $this->matrix[$r][$c]);
            }
        }
 
        return $result;
    }
 
    public function product(Matrix $matrix) : Matrix{
        if($this->columns !== $matrix->getRows()){
            throw new \InvalidArgumentException("Expected a matrix with $this->columns rows"); //????
        }
        $c = $matrix->getColumns();
        $result = new Matrix($this->rows, $c);
        for($i = 0; $i < $this->rows; ++$i){
            for($j = 0; $j < $c; ++$j){
                $sum = 0;
                for($k = 0; $k < $this->columns; ++$k){
                    $sum += $this->matrix[$i][$k] * $matrix->getElement($k, $j);
                }
                $result->setElement($i, $j, $sum);
            }
        }
 
        return $result;
    }
 
    public function determinant() : float{
        if($this->isSquare() !== true){
            throw new \LogicException("Cannot calculate determinant of a non-square matrix");
        }
        return match($this->rows){
            1 => $this->matrix[0][0],
            2 =>
                $this->matrix[0][0] * $this->matrix[1][1] -
                $this->matrix[0][1] * $this->matrix[1][0],
            3 =>
                $this->matrix[0][0] * $this->matrix[1][1] * $this->matrix[2][2] +
                $this->matrix[0][1] * $this->matrix[1][2] * $this->matrix[2][0] +
                $this->matrix[0][2] * $this->matrix[1][0] * $this->matrix[2][1] -
                $this->matrix[2][0] * $this->matrix[1][1] * $this->matrix[0][2] -
                $this->matrix[2][1] * $this->matrix[1][2] * $this->matrix[0][0] -
                $this->matrix[2][2] * $this->matrix[1][0] * $this->matrix[0][1],
            default => throw new \LogicException("Not implemented")
        };
    }
 
    public function __toString() : string{
        $s = "";
        for($r = 0; $r < $this->rows; ++$r){
            $s .= implode(",", $this->matrix[$r]) . ";";
        }
 
        return "Matrix({$this->rows}x{$this->columns};" . substr($s, 0, -1) . ")";
    }
 
}