You're not wrong, in that closed-form is not a clearly-defined term. However, mathematicians rarely do numerical calculations, so exp(), gamma, etc. are consid

You're not wrong, in that closed-form is not a clearly-defined term. However, mathematicians rarely do numerical calculations, so exp(), gamma, etc. are considered elementary functions, and there's no urgency to translate from symbols to numbers. Physicists who do calculations might be more restrictive about what closed-form means if they intend to compute a numeric result. https://en.wikipedia.org/wiki/Closed-form_expression https://en.wikipedia.org/wiki/Closed-form_expression Source: I studied pure mathematics, and we never used calculators - it was laughable, in fact. Most of our series never converged in the first place. :)