Help a brainlet /math/
how to do i write a periodic function giving the following results ..
0 0
1 -7/8
2 1/2
3 17/8
4 2
5 17/8
6 1/2
7 -7/8
8 0
9 -7/8
10 1/2
...
..
..
16 0
17 -7/8
...
Any help is appreciated