Assign numeric value to symbolic function a(k) for k=0

I have a symbolic matrix:

    bb(k)=[1,0;0,aa(k)];

I need to assign aa(0)=2 such that when I type bb(0) I get:

    bb(0)=[1,0;0,2];

Also, aa(1)=3 such that:

    bb(1)=[1,0;0,3];

How can this be achieved? Thanks!

Answer 1

[Walter Roberson]

syms bb(k)
aa = [2; 3];
bb(k) = [1;0;0,aa(k+1)];