Dear @Danilo,
As suggested by you, I worked on the 1. above to generate a 2D histogram.
However, there is a problem with multithreading as mentioned in my new post.
For your reference, I am attaching a sample ROOT file here and the code (2.4 KB).
I am running the code at the ROOT prompt as: .x rdf_his2D.cxx+
Any help is highly appreciated.
Regards,
Ajay