public function isFullRank()
    {
        for ($j = 0; $j < $this->n; ++$j) {
            if ($this->Rdiag[$j] == 0) {
                return false;
            }
        }
        return true;
    }
public function isFullRank()
    {
        for ($j = 0; $j < $this->n; ++$j) {
            if ($this->Rdiag[$j] == 0) {
                return false;
            }
        }
        return true;
    }
public function isFullRank ( ) { for ( $ j = 0 ; $ j < $ this -> n ; ++ $ j ) { if ( $ this -> Rdiag [ $ j ] == 0 ) { return false ; } } return true ; }
Is the matrix full rank?

@return boolean true if R, and hence A, has full rank, else false.
Is the matrix full rank?