A=rand(3)
B=A
B(end+1,end+2)=0
A =
0.9448 0.3377 0.1112
0.4909 0.9001 0.7803
0.4893 0.3692 0.3897
B =
0.9448 0.3377 0.1112
0.4909 0.9001 0.7803
0.4893 0.3692 0.3897
B =
0.9448 0.3377 0.1112 0 0
0.4909 0.9001 0.7803 0 0
0.4893 0.3692 0.3897 0 0
0 0 0 0 0
a=ones(9,1)
a(2:end)=2
b=cumprod(a)
A=diag(b)
a =
1
1
1
1
1
1
1
1
1
a =
1
2
2
2
2
2
2
2
2
b =
1
2
4
8
16
32
64
128
256
A =
1 0 0 0 0 0 0 0 0
0 2 0 0 0 0 0 0 0
0 0 4 0 0 0 0 0 0
0 0 0 8 0 0 0 0 0
0 0 0 0 16 0 0 0 0
0 0 0 0 0 32 0 0 0
0 0 0 0 0 0 64 0 0
0 0 0 0 0 0 0 128 0
0 0 0 0 0 0 0 0 256
B=diag(A)
B =
1
2
4
8
16
32
64
128
256