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<?php
/**
* File containing the abstract ezcGraphMatrix class
*
* @package Graph
* @version //autogentag//
* @copyright Copyright (C) 2005, 2006 eZ systems as. All rights reserved.
* @license http://ez.no/licenses/new_bsd New BSD License
*/
/**
* Provides a genereic matrix class with basic math operations
*
* @package Graph
*/
class ezcGraphMatrix
{
protected $columns;
protected $rows;
protected $matrix;
/**
* Constructor
*
* Creates a matrix with given dimensions. Optionally accepts an array to
* define the initial matrix values. If no array is given an identity
* matrix is created.
*
* @param int $columns Number of columns
* @param int $rows Number of rows
* @param array $values Array with values
* @return void
*/
public function __construct( $columns = 3, $rows = 3, array $values = null )
{
$this->columns = max( 2, (int) $columns );
$this->rows = max( 2, (int) $rows );
if ( $values !== null )
{
$this->fromArray( $values );
}
else
{
$this->init();
}
}
/**
* Create matrix from array
*
* Use the array values to set matrix values
*
* @param array $values Array with values
* @return ezcGraphMatrix Modified matrix
*/
public function fromArray( array $values )
{
for ( $i = 0; $i < $this->columns; ++$i )
{
for ( $j = 0; $j < $this->rows; ++$j )
{
$this->matrix[$i][$j] =
( isset( $values[$i][$j] )
? (float) $values[$i][$j]
: 0 );
}
}
return $this;
}
/**
* Init matrix
*
* Sets matrix to identity matrix
*
* @return ezcGraphMatrix Modified matrix
*/
public function init()
{
for ( $i = 0; $i < $this->columns; ++$i )
{
for ( $j = 0; $j < $this->rows; ++$j )
{
$this->matrix[$i][$j] = ( $i === $j ? 1 : 0 );
}
}
return $this;
}
/**
* Returns number of columns
*
* @return int Number of columns
*/
public function columns()
{
return $this->columns;
}
/**
* Returns number of rows
*
* @return int Number of rows
*/
public function rows()
{
return $this->rows;
}
/**
* Get a single matrix value
*
* Returns the value of the matrix at the given position
*
* @param int $i Row
* @param int $j Column
* @return float Matrix value
*/
public function get( $i, $j )
{
if ( !isset( $this->matrix[$i][$j] ) )
{
throw new ezcGraphMatrixOutOfBoundingsException( $this->columns, $this->rows, $i, $j );
}
return $this->matrix[$i][$j];
}
/**
* Set a single matrix value
*
* Sets the value of the matrix at the given position
*
* @param int $i Row
* @param int $j Column
* @param float $value Value
* @return ezcGraphMatrix Updated matrix
*/
public function set( $i, $j, $value )
{
if ( !isset( $this->matrix[$i][$j] ) )
{
throw new ezcGraphMatrixOutOfBoundingsException( $this->columns, $this->rows, $i, $j );
}
$this->matrix[$i][$j] = $value;
return $this;
}
/**
* Adds one matrix to the current one
*
* Calculate the sum of two matrices and returns the resulting matrix.
*
* @param ezcGraphMatrix $matrix Matrix to sum with
* @return ezcGraphMatrix Result matrix
*/
public function add( ezcGraphMatrix $matrix )
{
if ( ( $this->columns !== $matrix->columns() ) ||
( $this->rows !== $matrix->rows() ) )
{
throw new ezcGraphMatrixInvalidDimensionsException( $this->columns, $this->rows, $matrix->columns(), $matrix->rows() );
}
for ( $i = 0; $i < $this->columns; ++$i )
{
for ( $j = 0; $j < $this->rows; ++$j )
{
$this->matrix[$i][$j] += $matrix->get( $i, $j );
}
}
return $this;
}
/**
* Subtracts matrix from current one
*
* Calculate the diffenrence of two matices and returns the result matrix.
*
* @param ezcGraphMatrix $matrix subtrahend
* @return ezcGraphMatrix Result matrix
*/
public function diff( ezcGraphMatrix $matrix )
{
if ( ( $this->columns !== $matrix->columns() ) ||
( $this->rows !== $matrix->rows() ) )
{
throw new ezcGraphMatrixInvalidDimensionsException( $this->columns, $this->rows, $matrix->columns(), $matrix->rows() );
}
for ( $i = 0; $i < $this->columns; ++$i )
{
for ( $j = 0; $j < $this->rows; ++$j )
{
$this->matrix[$i][$j] -= $matrix->get( $i, $j );
}
}
return $this;
}
/**
* Scalar multiplication
*
* Multiplies matrix with the given scalar and returns the result matrix
*
* @param float $scalar Scalar
* @return ezcGraphMatrix Result matrix
*/
public function scalar( $scalar )
{
$scalar = (float) $scalar;
for ( $i = 0; $i < $this->columns; ++$i )
{
for ( $j = 0; $j < $this->rows; ++$j )
{
$this->matrix[$i][$j] *= $scalar;
}
}
}
/**
* Multiplies two matrices
*
* Multiply current matrix with another matrix and returns the result
* matrix.
*
* @param ezcGraphMatrix $matrix Second factor
* @returns ezcGraphMatrix Result matrix
*/
public function multiply( ezcGraphMatrix $matrix )
{
$mColumns = $matrix->columns();
if ( $this->columns !== ( $mRows = $matrix->rows() ) )
{
throw new ezcGraphMatrixInvalidDimensionsException( $this->columns, $this->rows, $mColumns, $mRows );
}
$result = new ezcGraphMatrix( $mRows, $mRows );
for ( $i = 0; $i < $this->columns; ++$i )
{
for ( $j = 0; $j < $mRows; ++$j )
{
$sum = 0;
for ( $k = 0; $k < $mColumns; ++$k ) {
$sum += $this->matrix[$i][$k] * $matrix->get( $k, $j );
}
$result->set( $i, $j, $sum );
}
}
return $result;
}
}
?>
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