• Jens Mueller (16/16) Jan 02 2012 Hi,

Jens Mueller <jens.k.mueller gmx.de> writes:

Hi,

in 2's complement the value T.min is special because its inverse is
itself. I'm using std.math.abs which computes the inverse using the
unary operator -. That's why it holds
assert(std.math.abs(int.min) == int.min)

Which is on one hand a bit strange because I'd expect the absolute of a
negative number to be positive. But on the other hand I see no way to
properly fix this. As the mathematical absolute of T.min is not in the
value range of T.
What is the post condition of std.math.abs? Must abs(x) >= 0 hold? One
could remove T.min from its definition range using a pre condition. This
is how it's done in C. But in D it should be done using contracts which
unfortunately will be compiled out in phobos (release mode is default).

In any case, IMHO the documentation needs clarification for this special
case.

Jens