function input problem

Hi,
Yesterday a took a look at rasmus last post about 3d voronoi ('3d voronoi-selecting only facede curves'),and had an idea(quite simple) to solve his problem.While i was correcting the definition i found an apparently simple problem.I used a function component  x=0 to check which distance i mesured was =0, and obtain a pattern to dispatch surfaces.
My input function x was:
3.214
8.712
12.878
0.0   
3.034
3.612
1.997
9.73
11.204
10.273
7.004
12.5
9.414
9.778
10.434
3.118
0.671
3.302
0.0
1.248
3.393
5.196
6.735
2.26 etc...

As you can see there are o values,but the function compnent 'see' these 0 numbers only if i extract integers values of these numbers.
So my question is,there are only some kind of numbers that i have to use with th f(x) component?
Thank you very much, and sorry for the noob question :)

Bye

Paolo