Thank you, @falk. I am not yet using pm.Data. I just mentioned that probably the solution lies there, as you also suggest. I will have to work on that, but the material that I have checked so far refers to uses of pm.Data where only one level exist. But the use of matrix multiplication is something that I need to do, also. It was on my todo list. Now it seems more necessary.
Quick related question: from a pur speed point of view, is it better to use matrix multiplication?