i would guess that because of how *** * floats are in binary computers, you have something like -0.0000000000000000000000000000000000001 and when you round it y

i would guess that because of how *** * floats are in binary computers, you have something like -0.0000000000000000000000000000000000001 and when you round it you end up with -0.0. Same goes for positive value, you're just not used to write the + sign before every number, so seeing the minus feels strange.