Re: 把390'角转换成30'角这个动作在数学上学名叫什么？

牛人阿，呵呵，这个功能说是取模也不是取模，余数不为0.
类似于取模，略有不同，结果在[1,limit]之间，不会有０。
@wrap(10,3)=1
@wrap(11,3)=2
@wrap(12,3)=3
@wrap(13,3)=1
......
lingo帮助：
@WRAP( INDEX, LIMIT)
This allows you to @wrap an index around the end of a set and continue indexing at the other end of the set. That is, when the last (first) member of a set is reached in a set looping function, use of @WRAP will allow you to wrap the set index to the first (last) member of the set. This is a particularly useful function in cyclical, multiperiod planning models.
Formally speaking, @WRAP returns J such that J = INDEX - K * LIMIT, where K is an integer such that J is in the interval [1,LIMIT]. Informally speaking, @WRAP will subtract or add LIMIT to INDEX until it falls in the range 1to LIMIT.
For an example on the use of the @WRAP function in a staff scheduling model, refer to the Primitive Set Example section in Using Sets.
共勉
多谢  toctory 。