Code Examples -> Matrix Class (PHP5 and up)

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PHP Code Examples

Title :	Matrix Class (PHP5 and up)
Categories :	PHP, PHP Classes, Arrays	Exception e
Date :	Jul 31st 2005
Grade :	2 of 5 (graded 5 times)
Viewed :	8050
File :	No file for this code example.
Images :	No Images for this code example.

Search :	More code by Exception e
Action :	Grade This Code Example
Tools :	My Examples List

Code

<?php
/**
* Basic class for matrix operations
*
*/
class Matrix        {

        /**
        * the matrix, a two dimensional array
        * @var array
        */
        private $matrix;

        /**
        * total of rows of the matrix
        * @var int
        */
        private $rowCount = 0;

        /**
        * total of columns of the matrix
        * @var int
        */
        private $columnCount = 0;

        /**
        * Constructs a new Matrix based on the two-dimensional that is passed in
        * @param array $matrix a two-dimensional array. $matrix is passed by reference
                                        and should be indexed without gaps, starting from 0!
                                        the first dimension contains arrays which are the rows
        */
        function __construct(&$matrix)        {
                $this->matrix                =& $matrix;
                $this->rowCount                = count($matrix);
                $this->columnCount        = count(current($matrix));
                //parent::__construct($array);
        }

        /**
        * returns the row of the matrix at position $index
        * if $index is an invalid key of the row, an exception will be thrown
        * @param int $index key of the row that has to be retrieved. possible values ranges from 0 to numberOfRows - 1
        * @return array
        */
        function getRow($index)        {
                if (!array_key_exists($index, $this->matrix))        {
                        throw new Exception('invalid row index provided');
                }
                return $this->matrix[$index];
        }

        /**
        * returns the column of the matrix at position $index
        * if $index is an invalid key of the row, an exception will be thrown
        * @param int $index key of the row that has to be retrieved. possible values ranges from 0 to numberOfRows - 1
        * @return array
        */
        function getColumn($index)        {
                $res = array();

                if ($index > $this->columnCount - 1 || $index < 0)        {
                        throw new Exception('invalid column index provided');
                }
                foreach ($this->matrix as $row)        {
                        $res[] = $row[$index];
                }
                return $res;
        }

        /**
        * multiply $rhs with this Matrix
        * @param mixed $rhs
                        if $rhs is numeric, each value of this matrix is multiplicated by $rhs (so called scalar multiplication)
                        if $rhs is a Matrix, a ordinary matrix product wil be returned
                        see <a href="http://en.wikipedia.org/wiki/Matrix_multiplication">http://en.wikipedia.org/wiki/Matrix_multiplication</a> for a formal explanation
        * @return Matrix new Matrix-object as the result of the operation
        */
        function multiply($rhs)        {
                if (is_numeric($rhs))        {
                        return $this->multiplyByNumber($rhs);
                } elseif ($rhs instanceof Matrix)        {
                        return $this->multiplyByMatrix($rhs);
                } else        {
                        throw new Exception('invalid operand');
                }
        }

        /**
        * sums this and $rhs matrix.
        * The dimensions of the both matrices have to be te same.<br>see <a href="http://en.wikipedia.org/wiki/Matrix_%28mathematics%29#Sum">http://en.wikipedia.org/wiki/Matrix_%28mathematics%29#Sum</a> for a formal explanation
        * @param Matrix $rhs
        * @return Matrix new Matrix-object as the result of the operation
        */
        function sum(Matrix $rhs)        {
                if ($rhs->rowCount !== $this->rowCount && $rhs->columnCount !== $this->columnCount)        {
                        throw new Exception('matrices cannot be added, because they have different dimensions');
                }

                for ($i = 0; $i < $this->rowCount; $i++)        {
                        $res[$i] = array();
                        for ($j = 0; $j < $this->columnCount; $j++)        {
                                $res[$i][$j] = $this->matrix[$i][$j] + $rhs->matrix[$i][$j];
                        }
                }
                return new Matrix($res);
        }

        /**
        * subtracts $rhs from this matrix
        * The dimensions of the both matrices have to be te same. Works like sum(), but this time the operation is subtract<br>
        * @param Matrix $rhs
        * @return Matrix new Matrix-object as the result of the operation
        */
        function minus(Matrix $rhs)        {
                if ($rhs->rowCount !== $this->rowCount && $rhs->columnCount !== $this->columnCount)        {
                        throw new Exception('matrices cannot be subtracted, because they have different dimensions');
                }

                for ($i = 0; $i < $this->rowCount; $i++)        {
                        $res[$i] = array();
                        for ($j = 0; $j < $this->columnCount; $j++)        {
                                $res[$i][$j] = $this->matrix[$i][$j] - $rhs->matrix[$i][$j];
                        }
                }
                return new Matrix($res);
        }

        function numberOfRows()        {
                return $this->rowCount;
        }

        function numberOfColumns()        {
                return $this->columnCount;
        }

        /**
        * HTML representation of the Matrix
        * only for debugging purposes
        * @return string table
        *
        */
        function __toString()        {
                $s = '<table border="1">';
                for ($i = 0; $i < $this->rowCount; $i++)        {
                        $s .= '<tr>';
                        for ($j = 0; $j < $this->columnCount; $j++)        {
                                $s .= '<td>'.$this->matrix[$i][$j].'</td>';
                        }
                        $s .= '</tr>';
                }
                return $s.'</table>';
        }

        private function multiplyByNumber($number)        {
                for ($i = 0; $i < $this->rowCount; $i++)        {
                        $res[$i] = array();
                        for ($j = 0; $j < $this->columnCount; $j++)        {
                                $res[$i][$j] = $this->matrix[$i][$j] * $number;
                        }
                }
                return new Matrix($res);
        }

        private function multiplyByMatrix(Matrix $rhs)        {
                if ($this->columnCount !== $rhs->rowCount)        {
                        throw new Exception('The matrices cannot be multiplied');
                }
                $res = array();

                for ($i = 0; $i < $this->rowCount; $i++)        {
                        $res[$i] = array();
                        for ($j = 0; $j < $rhs->columnCount ; $j++)        {
                                $res[$i][$j] = 0;
                                for ($k = 0; $k < $this->columnCount; $k++)        {
                                        $res[$i][$j] += $this->matrix[$i][$k] * $rhs->matrix[$k][$j];
                                }
                        }
                }
                return new Matrix($res);
        }
}
?>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>Matrix</title>
</head>
<h1>Example</h1>
<body>
<?php
$a = array(
                array(1,2,3),
                array(1,2,0)
        );
$b = array(
                array(2,4,6),
                array(4,5,4),
                array(1,1,0),
        );

$mA = new Matrix($a);
$mB = new Matrix($b);

$multiply = $mA->multiply($mB);

// what's in it?
echo $multiply->__toString();
echo '<hr>';
echo $mA->multiply(6);
?>
</body>
</html>

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User Comments

	Shea Sollars wrote : 1339 `VERY nice.`
	Joost Langen wrote : 1341 I tried to test your script, but did`t succeed. this is the error: " Parse error: parse error, unexpected T_STRING, expecting T_OLD_FUNCTION or T_FUNCTION or T_VAR or `}` in /home/resellers/841289/841289/josefem.nl/www/test/matrix.php on line 12 " I can`t see what`s wrong. gr Joost
	Exception e wrote :1342 In response to Joost Langen I`ve sent a private message, but I realised that more people can have the same problem as Joost has. Therefore, I repeat my answer here: I think that your php version is too low. In order to run this code you need at least PHP5. If you want to check your php version, just have a look at php_info or simply call <?php echo `my php version is: `.PHP_VERSION; ?> In order to run this code under PHP4, you should strip of the `private` keywords and replace the exceptions with errors. For example: trigger_error(`invalid row index provided`, E_USER_ERROR); But I like to encourage the use of PHP5... :)