code: public function equal($z)
      {
          if (is_numeric($z)) {
              $z = new self($z, 0);
          }
  
          return ($z->real == $this->float_r) && ($z->imaginary == $this->float_i);
      }
docs: Tests whether given `z` complex number is equal to the current complex
  number.
  
  @param  mixed   $z Complex or real number
  @access public
  @return boolean