Re: [boost] Optimized portable isnan, isfinite, fpclassify etc

From: Johan Råde (rade_at_[hidden])
Date: 2006-11-09 09:00:41

John Maddock wrote:
> Johan Råde wrote:
> 
>> That is weird.
>> Can you run the inspect tool (fpclassify/tools/inspect/inspect.cpp)
>> on Win32 / Intel 7?
> 
> I don't think it differs from any other Win32 compiler:
> 
> s. nan    ff 80 00 00

It certainly does differ. All bits in the mantissa are zero.
It is the IEEE754 binary representation of negative infinity.

Here is what I get on my Win32 / MSVS 7.1 / ia32 platform

s. nan    7f 80 00 01

There is the same problem for double and long double.

Looks like Intel 7 on Win32 has a broken 
numeric_limits<T>::signalling_NaN().

--Johan