Imagine you have two quantities a and b in a TTree, and you would like to draw a+b. That’s straightforward to do.
But one can imagine more complicated formulas, and also one can imagine that a person who reads the TTree doesn’t know which formula is to be used. In that case, it would be nice if a virtual branch could be stored in the TTree which contains the formula, so that you can draw c to obtain a+b.
The way I mean this is like views in relational database systems, such that the value of c is not stored in the tree, but computed on the fly.
Does such functionality exist?