On Tue, 08 Aug 2006 11:46:01 +0200, Warp <war### [at] tagpovrayorg> wrote:
> Alain <ele### [at] netscapenet> wrote:
>> OK then. So, as long as your results STAY in the FPU and you keep on  
>> reusing
>> them, you can keep an improved acuracy. But, as soon as you need to put  
>> your
>> results anywhere else, you fall back to 64 bits acuracy.
>
>   Not really. You can store the numbers in memory using the 80-bit
> accuracy. In C/C++ you can usually do that with the 'long double' type.

Not with a Microsoft C++ compiler though. In their infinite wisdom they  
chose the 64-bit type for both 'double' and 'long double'.


>   I don't know, however, if there's a speed penalty in storing/reading
> memory in units larger than 64 bits...

There was on the original Pentium. Newer processors may have wider data  
paths though.


-- 
FE

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