Neos\Flow\Validation\Validator\FloatValidator::isValid PHP Method

    protected function isValid($value)
    {
        if (is_float($value)) {
            return;
        }
        if (!is_string($value) || strpos($value, '.') === false || preg_match('/^[0-9.e+-]+$/', $value) !== 1) {
            $this->addError('A valid float number is expected.', 1221560288);
        }
    }