public function mean() : ColumnVector
    {
        if ($this->n < 1) {
            throw new RuntimeException('Median is not defined for matrices'
                . ' with less than 1 column.');
        }

        return $this->sum()->divide($this->n);
    }
public function mean() : ColumnVector
    {
        if ($this->n < 1) {
            throw new RuntimeException('Median is not defined for matrices'
                . ' with less than 1 column.');
        }

        return $this->sum()->divide($this->n);
    }
public function mean ( ) : ColumnVector { if ( $ this -> n < 1 ) { throw new RuntimeException ( 'Median is not defined for matrices' . ' with less than 1 column.' ) ; } return $ this -> sum ( ) -> divide ( $ this -> n ) ; }
Compute the means of each row and return them in a vector.

@throws \InvalidArgumentException
@return \Rubix\Tensor\ColumnVector
Compute the means of each row and return them in a vector .