AMDG On 03/08/2011 11:03 AM, Rhys Ulerich wrote:
The usual std::min and std::max prefer numbers over NaNs per http://en.wikipedia.org/wiki/IEEE_754_revision#min_and_max. POSIX's fmin(3) does as well.
Can anyone suggest a better implementation (chained ternary complaints aside) for a NaN-preferring min or max than brute force things akin to
template<class T> inline const T& minnan(const T& a, const T& b) { return UNLIKELY((boost::math::isnan)(a)) ? a : (a< b) ? a : b; }
where UNLIKELY is a small macro telling the compiler to generate code expecting that the boost::math::isnan test fails?
The need arises in a numerical simulation where I want to gradually accumulate a global minimum where throwing away NaNs ("windowing" in IEEE 754 revision-speak) is the unacceptable.
How about: template<class T> inline const T& minnan(const T& a, const T& b) { return !(b <= a)? a : b; } In Christ, Steven Watanabe