http://en.wikipedia.org/wiki/Nearest_integer_function x-[x] (nearest integer) is zero for -3, -2, -1, 0, 1, 2, 3. Within the range from 0 to 0.5, [x] = 0 so x-[x]=x. Then from 0.5 to 1.5, [x]=1 so x-[x]=x-1 which will be zero at x=1. And so on. There will be segments with slope 1 followed by a ...