code: public function multiplyAllow($matrix)
      {
          if (is_numeric($matrix)) {
              return true;
          }
  
          if ($matrix instanceof Complex) {
              return true;
          }
  
          if ($matrix instanceof Matrix) {
              return $this->size->cols == $matrix->rows;
          }
  
          return false;
      }
docs: Tests whether the current matrix can be multiply with the given one.
  
  @param  mixed   $matrix Scalar, complex or matrix
  @access public
  @return boolean