Question: Consider the following C++ code:

```
double someZero = 0;
std::cout << 0 - someZero << '\n';   // prints 0
std::cout << -someZero << std::endl; // prints -0

```

The question arises: what is negative zero good for, and should it be defensively avoided (i.e. use subtraction instead of smacking a minus onto a variable)?

Answer: 
From Wikipedia:

> 
> It is claimed that the inclusion of signed zero in IEEE 754 makes it much easier to achieve numerical accuracy in some critical problems[1], in particular when computing with complex elementary functions[2].
> 
> 
> 

The first reference is "Branch Cuts for Complex Elementary Functions or Much Ado About Nothing's Sign Bit" by W. Kahan, that is available for download [here](https://people.freebsd.org/~das/kahan86branch.pdf).

One example from that paper is `1/(+0)` vs `1/(-0)`. Here, the sign of zero makes a huge difference, since the first expression equals `+inf` and the second, `-inf`.
I'm making a measuring app, and the -0 is very useful for mixed numbers (such as separating into feet and inches).

Imagine that we have a variable "length" that we're trying to separate into "feet" and "inches".

(This is java code, but the same idea is true for C++).

```
feet = Math.signum(length) * Math.floor(Math.abs(length / 12));
// could also do feet = length>0 ? Math.floor(length / 12) : Math.ceil(length / 12)
inches = Math.abs(length) % 12;

```

If the length is between -1 feet and 0 feet, we'd want it to say -0 for the feet so we know it's negative.