How to test if float is NaN?

[Don Clugston]

Jarrett Billingsley wrote:
> "Don Clugston" <dac at nospam.com.au> wrote in message 
> news:e5e621$2232$1 at digitaldaemon.com...
> 
>> I really think that 'real' should not be viewed as a built-in type, it 
>> should be a typedef, since that's how it behaves.
>> The built-in types could have really obscure names to discourage their 
>> use:
>> eg
>> typedef float80pad96 real;  // a Linux32 80-bit real
>> typedef float80pad128 real; // a Linux64 80-bit real
>> typedef float80pad80 real;  // a Win32 80-bit real
> 
> I agree.
> 
>> (a) Are there any signs of Intel or AMD actually implementing 128 -bit 
>> floats?
> 
> Well, as far as I know (and as you probably already know and could have been 
> on the designing committee for it), 

LOL! I am just a humble cheesemaker.

IEEE has already defined the 754 spec
> for 128-bit floats.  Considering that we've got (I suppose) 10-15 years 
> before the 128-bit processor generation begins, and considering the 
> ever-increasing demand for multimedia and floating-point performance, and 
> considering Intel/AMD's desire to phase out x87 instructions in favor of the 
> SSE/2/3/4 instructions (which have 32- and 64-bit float support already), 
> I'd say the chances of 128-bit floats being created, maybe in just a couple 
> years, is pretty high.  SSE5? 

It seems clear that all future developments in floating point hardware 
will be driven by games, and not by science (that's already true of MMX 
and SSE). But maybe there is a market for 128-bit FP for graphics.

I just found a graphics card that is already using 128-bit floats:

http://www.firingsquad.com/hardware/radeon_9700/page2.asp

I *hope* they're using IEEE 754r.