code: public static function IMAGINARY($complexNumber)
      {
          $complexNumber = Functions::flattenSingleValue($complexNumber);
  
          $parsedComplex = self::parseComplex($complexNumber);
  
          return $parsedComplex['imaginary'];
      }
docs: IMAGINARY.
  
  Returns the imaginary coefficient of a complex number in x + yi or x + yj text format.
  
  Excel Function:
  IMAGINARY(complexNumber)
  
  @category Engineering Functions
  
  @param string $complexNumber the complex number for which you want the imaginary
  coefficient
  
  @return float