public function getFormula()
	{
		$expression	= "";
		for( $i = $this->getRank() - 1; $i >= 0; $i-- )
		{
			$a = $this->coefficients[$i];
			if( $a != 0 )
			{
				$sign = $this->getSign( $a );
				if( $i )
				{
					if( abs( $a ) == 1 )
					{
						if( $expression || $a == -1 )
							$expression	.= $sign;
					}
					else
						$expression	.= $expression ? $sign.abs( $a )."*" : $a."*";
					$expression	.= "pow(x,".$i.")";
				}
				else
					$expression	.= $expression ? $sign.abs( $a ) : $a;
			}
		}
		$formula	= new Alg_Math_Formula( $expression, "x" );
		return $formula;
	}