matlab

>> a = [1 2 3];
>> repmat(a,2,3) 
ans =

     1     2     3     1     2     3     1     2     3
     1     2     3     1     2     3     1     2     3

>> a = [6 3 2 1 4 5];
>> [~,ans] = sort(a) % 默认从小到大的索引值
ans =

     4     3     2     5     6     1
>> a(ans)

ans =

     1     2     3     4     5     6

>> a = ones(3);
>> a(1,(4:5)) = 10

a =

     1     1     1    10    10
     1     1     1     0     0
     1     1     1     0     0