What is "-0.0"

[Morgan Cheng]

In java 6.0, I have below code.
double x = 0.0;
double y = -10.0;
double z = x / y;
System.out.println("z = " +z);

The result is "-0.0". This is wired, why it is negative zero?

 

[Richard Reynolds]

In java 6.0, I have below code.
double x = 0.0;
double y = -10.0;
double z = x / y;
System.out.println("z = " +z);

The result is "-0.0". This is wired, why it is negative zero?

http://en.wikipedia.org/wiki/−0_(number)

 

[Patricia Shanahan]

In java 6.0, I have below code.
double x = 0.0;
double y = -10.0;
double z = x / y;
System.out.println("z = " +z);

The result is "-0.0". This is wired, why it is negative zero?

I agree that it is weird, but there are reasons why IEEE 754 floating
point arithmetic distinguishes positive and negative zero.

A zero may be a stand-in for a number of very small absolute magnitude.
There are some algorithms where intermediate results overflow and
underflow, but the final answer is representable.

Preserving the sign on underflow, and through arithmetic using a zero,
also preserves the sign on division by the result of the underflow,
leading to the correct choice between positive and negative infinity.

Patricia

 

[Stefan Ram]

The result is "-0.0". This is wired, why it is negative zero?

The first result for

http://google.to/search?q=negative+zero

currently is

http://en.wikipedia.org/wiki/−0_(number)

.

 

[Roedy Green]

The result is "-0.0". This is wired, why it is negative zero?

Because floating point has both a positive and negative 0, signed
magnitude, unlike ints. see http://mindprod.com/jgloss/ieee754.html