Hello.

How could I make a description of the function which relate an argument and a value this way:

x y

0 0

1 1

2 2

...

6 6

7 5

8 4

...

12 0

13 1

14 2

etc...

This is obviously periodic function, so I can write that f(x)=f(x+12) but how could I give a comprehensive formula for order of y? Should I write piecewise definition or rather recursive, or...?

Thanks for all help.