# HypExp and HPL packages for hypergeometric functions: Evaluating a function HPL[{minus,plus},x]?

I am currently using the HypExp and HPL packages, which are useful for expanding hypergeometric functions in series around integer or half-integer values, as in common in dimensional regularization for particle physics calculations.

Expanding a certain hypergeometric function gives me something of the form

HPL[{minus,plus}, x]


This is odd because HPL should only take integer values where "minus" and "plus" appear; furthermore, this function cannot be reduced by the packages. I am running Mathematica v. 11. Can anyone offer some help?

• Maybe you should read their paper more carefully. – Wen Chern Dec 4 '18 at 22:54
• I have read them carefully and found no solution, or even any mention of "minus" or "plus". – Dwagg Dec 5 '18 at 2:51
• Perhaps it might be worth just emailing the authors of this package directly. Usually, there aren't many users of such specialized packages on here. So I wouldn't hold your breath on an answer. – QuantumDot Dec 5 '18 at 5:38
• One note, instead of MathJAX it is preferable for us to have the code (if the expression of interest is in fact a Mathematica expression). – b3m2a1 Dec 5 '18 at 7:15
• The solution is to use HPLpm21m1 to convert this special function to known functions. I hope I can leave this up here in case it is helpful to somebody else. – Dwagg Dec 5 '18 at 15:36