例6-19  spalloc函數的使用。
解：在命令窗口中輸入如下命令，并按Enter鍵確認。
>> n=4;
>>  v=sprand(4,1,0.2)
v =
   (3,1)       0.9218
>> s = spalloc(n,n,1*n);
        for j = 1:n
            s(:,j) = (v)
        end
s =
   (3,1)       0.9218
s =
   (3,1)       0.9218
   (3,2)       0.9218
s =
   (3,1)       0.9218
   (3,2)       0.9218
   (3,3)       0.9218
s =
   (3,1)       0.9218
   (3,2)       0.9218
   (3,3)       0.9218
   (3,4)       0.9218
>>