1.setdiff函数
set difference.
C=setdiff(A,B) for vector A and B, return the values in A that are not in B with no repetitions. C will be sorted.
对于向量A,向量B，C=setdiff(A,B)函数返回在向量A中却不在向量B中的元素，并且C中不包含重复元素，并且从小到大排序。
[C,IA] = setdiff(A,B) also returns an index vector IA such that C = A(IA). If there are repeated values in A that are not in B, then the index of the first occurrence of each repeated value is returned.
返回值C同上，IA是C中元素在向量A中的下标（索引）。如果A中存在重复元素，并且该元素不在B中，就返回重复元素的第一次出现的下标。
2.例子
>> a = [9 9 9 9 9 9 8 8 8 8 7 7 7 6 6 6 5 5 4 2 1] ;>> b = [1 1 1 3 3 3 3 3 4 4 4 4 4 10 10 10] ;
>> [c1,ia1] = setdiff(a,b)
c1 =
2 5 6 7 8 9
ia1 =
20
17
14
11
7
1
后面用到其他功能的在写(*^▽^*)