I’m looking at the algorithm for calculating `grad_F32`

and working on getting the tests I wrote to pass. One of the things that comes up is that even when 3F2 power series representation is defined, the gradient power series is not as the gradient power series relies on the digamma function, which is not finite at negative integers. Current behavior is to return wrong results. My preferred solution is to make it throw for negative integer arguments in addition to throwing when 3F2 will not converge (it must meet those conditions as well).

The only reason this wouldn’t be a great bugfix is if we know that there are some models that relay on traversing that space (over a negative integer in 3F2(a1,a2,a3,b1,b2,z). Anyone know for sure either way?

I think this is the last thing I have to tackle before I can wrap up that bugfix PR.