A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Sorry for the intrusion, but what exactly are you trying to do? GPT is not and Excel function. At least not in my version.
Formulas like: =GPT(A3&" "&C1&" "&D1&" "&E1) and =GPT(A2+A, C1:E1) are nonsense.
It would be more helpful if you could upload a screenshot showing the row and column headers, the data you work with and the expected results.