Hi Sander,
Sorry I wasn't very careful in writing my question. so let me rephrase it. Yes by "Tr" I mean the trace and by "." the dot product. If I write:
mata = {{a, 0}, {0, 0}};
matb = {{b, 0}, {0, 0}};
matc = {{c, 0}, {0, 0}};
And then
Tr[mata.matb.matc]
Tr[matb.mata.matc]
The output is
a b c
a b c
which is fine if a,b and c are numbers. However, if they are matrices, then in general Tr[a.b.c] and Tr[b.a.c] are different. So I would like to keep track of this, without having to define a, b and c.
