>> A=[1,2,3;4,5,6;7,8,9],B=[1,2;3,4]
A =
1 2 3
4 5 6
7 8 9
B =
1 2
3 4
>> [rA,cA]=size(A); %得到A大小
>> [rB,cB]=size(B);
>> C=zeros(max(rA,rB),max(cA,cB));%得到A和B最大的行列
>> C(1:rA,1:cA)=A;%把C填充為A
%在下面進行加減乘除
>> C(1:rB,1:cB)=C(1:rB,1:cB)+B;%再去相加對應的B行列
>> C
C =
2 4 3
7 9 6
7 8 9