Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Calculation/Engineering.php
public static function IMAGINARY($complexNumber)
    {
        $complexNumber = Functions::flattenSingleValue($complexNumber);

        $parsedComplex = self::parseComplex($complexNumber);

        return $parsedComplex['imaginary'];
    }
public static function IMAGINARY($complexNumber)
    {
        $complexNumber = Functions::flattenSingleValue($complexNumber);

        $parsedComplex = self::parseComplex($complexNumber);

        return $parsedComplex['imaginary'];
    }
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