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From: Willem <willem@turtle.stack.nl>
Newsgroups: comp.programming
Subject: Re: 64 bit code
Date: Sat, 13 Oct 2012 12:34:57 +0000 (UTC)
Organization: Stack Usenet News Service
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BartC wrote:
) If the hardware can directly deal with 64-bit floats, then there is little 
) performance loss (compared with attempting 64-bit arithmetic on 32-bit 
) hardware, or in software).
)
) The only issue might be memory bandwidth when dealing with large numbers of 
) floating point values, although if they are accessed mainly for calculation, 
) then it's possible the calculation will dominate the timings.

Most CPU's nowadays can do parallel computations on 4 32-bit floats at the
same time, thus effectively quadrupling the speed.

) Anyway, I remember using 32-bit floats in an application (originally using 
) software emulation), and they weren't of sufficient accuracy for some types 
) of problems (mapping for example). They only have 1 in 8 million precision 
) after all. Switching to 64-bits solved that problem.
)
) Sometimes there are ways to get around such problems, and continue using 
) 32-bits, but sometimes also it's simpler to just use 64!

The point is that sometimes, using 32-bit floats is the best option.
Showing cases where 64-bit is the best option is irrelevant to that
position.


SaSW, Willem
-- 
Disclaimer: I am in no way responsible for any of the statements
            made in the above text. For all I know I might be
            drugged or something..
            No I'm not paranoid. You all think I'm paranoid, don't you !
#EOT