In what context do you use it? I use a “mod” operator all the time for floating point calculations, and have never come across a need for the other one.

As one simple example, it is frequently useful to map floats into the range [0, 2π), but I have never once wanted to map positive floats into the range [0, 2π) while negative floats get mapped into (–2π, 0] by the same code.