code: public function divide($z)
      {
          if (is_numeric($z)) {
              $z = new self($z, 0);
          }
  
          if ($z->is_zero) {
              throw new \InvalidArgumentException('Cannot divide by zero!');
          }
  
          $divisor = pow($z->re, 2) + pow($z->im, 2);
  
          $r = ($this->float_r * $z->re) + ($this->float_i * $z->im);
          $i = ($this->float_i * $z->re) - ($this->float_r * $z->im);
          $r = $r / $divisor;
          $i = $i / $divisor;
  
          return new self( $r, $i);
      }
docs: Divides current complex number with another.
  
  @throw \InvalidArgumentException If argument is zero
  @param  mixed   $z Complex or real number
  @access public
  @return Complex