Where in A should d go?
Note that A is going to be an n^2 by n^2 array as you put something of length n^2 along the main diagonal, and the other two diagonals have had their length adjusted properly to be consistent.
Note that d is going to be an (n^2+3) by (n^2+3) array, as the length of the third diagonal is n^2, so the length of the second diagonal would be n^2 + 1 so the length of the first diagonal would be n^2 + 2 so the length of the main diagonal would be n^2 + 3.
So you cannot put d within A. You could put A within d.
What I suspect you want is to fix your sizes for d1 and d2, and then use
A = A + d
