Treatment of -0

[ViralBShah]

We seem to convert -0 to 0. The signbit of 0 should be preserved, and -0 should be displayed if signbit is -1.

julia> signbit(0)
1

julia> signbit(-0)
1

MATLAB keeps the sign on zero, but doesn't display it, and even computes sin(-0) as -0.

x = +0

x =

0000000000000000

x = -0

x =

8000000000000000

This stems from the discussion as per http://math.mit.edu/~numericalmath/numericalmath/index.php/Sine, where

sin(-0) should be -0

[StefanKarpinski]

This is not a bug. There is no negative zero for integer types: -0 is 0. The only reason this works in Matlab is that 0 is actually 0.0 and -0.0 does have a negative sign bit. In Julia, this doesn't happen because 0 is actually an integer.