Re: [boost] Ann: Floating Point Utilities Review starts today

From: John Maddock (john_at_[hidden])
Date: 2008-02-27 11:31:46

Johan Råde wrote:
>> There is one other useful function worth having IMO:
>>
>> template <class T>
>> int sign(T x);
>>
>> returns 0 (x is zero), +1 (x is > 0) or -1 (x is < 0).  This is
>> trivial to implement (lot's of old C code - for example the
>> Numerical Recipies stuff - implement this as a helper macro), and
>> there's an undocumented version currently in Boost.Math.  Is this
>> worth integrating with Johan's code?  I've found it quite useful in
>> Boost.Math from time to time.
>
> What should this function return for a NaN?

In any of the use cases I have for that function, it would be an error to be 
trying to handle NaN's.  So it's a domain error I guess.

John.