TF2 constructor from "compiled" function

Hi experts,

I’ve just spent a few hours trying to use the TF2 constructor using a “compiled” function. The class reference has no description what will be sent to the function the user provides (Double_t(*)(Double_t *, Double_t *) fcn). I thought these are both pointers to the inputs and was surprised to get a null pointer for the second argument. I actually wondered why they were implemented as pointers but the answer wasn’t obvious to me. I think I finally figured out that the first one is an array of arguments, and the second is an array of parameters. It would be nice if these are included in the class reference. Thanks a lot!

Thanks for reporting. We will add more information .

I think the TF1 ref guide you give more details: … 575c0f6c20

Also this example helps:

and this part of the user’s guide: … tion-class

Thanks a lot!