Numerically they are equal.
z = 0;
mz = -0;
z == mz
However, they are not identical.
format hex
z
mz
Note that the sign bits are different. You can see this:
format
plusInf = 1/z
minusInf = 1/mz
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
...
If y is ±0 and x is negative or -0, ±π is returned
This is specifically called out in section 9.2.1 of IEEE 754-2008.
