WorksheetFunction. Sum will work with either a range or a 2 dimentional array. It errors because you are passing it a 3 dimensional array.
I'm going to take you literally when you say "I'm trying to solve the simple case of a (3,3,3) matrix with each element equal to some double, a". This will do that.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.