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Re: What Floating-Point Precisions Would Physicists Prefer?

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On Thu, 06 Aug 2015 14:11:40 -0700, Quadibloc wrote:

> 
> If calculating with such numbers "takes a lot of time", then such an option, to 
> decrease exponent range, is reasonable
>

Reducing exponent range will only create a larger and larger unusable interval
around zero, and this would be counterproductive to many applications.

>
> It doesn't reduce the precision or accuracy of calculations that don't involve 
> very small numbers.
> 

No.  That's why "flush to zero" in entirely optional.


>
> However, for such calculations _to_ take a lot of time means that IEEE 754 was 
> not implemented correctly on the processor
>

IEEE 754 only specifies what to accomplish and not so much how to accomplish it.

The fact that denormal numbers take longer to process is a natural consequence
of hardware registers, which are designed for the normalized format.  Thus
a lot of pre-processing for each denormal number is required.  Off the top of
my head, arithmetic on normalized FP takes about 4-5 machine cycles whereas
denormals require about 20-50 machine cycles.  In algorithms that involve much
looping this can add up.

Denormals are a way to avoid the large "gap" around zero and they are very
good to have.

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Thread

What Floating-Point Precisions Would Physicists Prefer? Quadibloc <jsavard@ecn.ab.ca> - 2015-08-04 20:41 -0700
  Re: What Floating-Point Precisions Would Physicists Prefer? Fabian Russell <root@localhost.localdomain> - 2015-08-05 05:14 +0000
    Re: What Floating-Point Precisions Would Physicists Prefer? Quadibloc <jsavard@ecn.ab.ca> - 2015-08-05 04:38 -0700
      Re: What Floating-Point Precisions Would Physicists Prefer? Fabian Russell <root@localhost.localdomain> - 2015-08-05 14:22 +0000
        nano-M-sets noTthaTguY <abu.kuanysh05@gmail.com> - 2015-08-05 13:14 -0700
          Re: nano-M-sets Fabian Russell <root@localhost.localdomain> - 2015-08-05 21:23 +0000
            Re: nano-M-sets Poutnik <poutnik4nntp@gmail.com> - 2015-08-06 08:16 +0200
              Re: nano-M-sets Fabian Russell <root@localhost.localdomain> - 2015-08-06 17:34 +0000
                Re: nano-M-sets Quadibloc <jsavard@ecn.ab.ca> - 2015-08-06 11:23 -0700
                Re: nano-M-sets Fabian Russell <root@localhost.localdomain> - 2015-08-06 18:39 +0000
                Re: nano-M-sets Poutnik <poutnik4nntp@gmail.com> - 2015-08-06 21:07 +0200
                Re: nano-M-sets Fabian Russell <root@localhost.localdomain> - 2015-08-06 19:14 +0000
                Re: nano-M-sets Poutnik <poutnik4nntp@gmail.com> - 2015-08-07 07:41 +0200
                Re: nano-M-sets Quadibloc <jsavard@ecn.ab.ca> - 2015-08-06 14:17 -0700
                Re: nano-M-sets Fabian Russell <root@localhost.localdomain> - 2015-08-06 21:36 +0000
                Re: nano-M-sets Poutnik <poutnik4nntp@gmail.com> - 2015-08-07 08:08 +0200
                Re: nano-M-sets Poutnik <poutnik4nntp@gmail.com> - 2015-08-06 21:05 +0200
        Re: What Floating-Point Precisions Would Physicists Prefer? Quadibloc <jsavard@ecn.ab.ca> - 2015-08-06 11:18 -0700
          Re: What Floating-Point Precisions Would Physicists Prefer? Fabian Russell <root@localhost.localdomain> - 2015-08-06 19:03 +0000
            Re: What Floating-Point Precisions Would Physicists Prefer? Quadibloc <jsavard@ecn.ab.ca> - 2015-08-06 14:11 -0700
              Re: What Floating-Point Precisions Would Physicists Prefer? Fabian Russell <root@localhost.localdomain> - 2015-08-06 21:51 +0000
                Re: What Floating-Point Precisions Would Physicists Prefer? Quadibloc <jsavard@ecn.ab.ca> - 2015-08-06 15:18 -0700
                Re: What Floating-Point Precisions Would Physicists Prefer? Fabian Russell <root@localhost.localdomain> - 2015-08-07 01:11 +0000
                Re: What Floating-Point Precisions Would Physicists Prefer? noTthaTguY <abu.kuanysh05@gmail.com> - 2015-08-07 10:25 -0700
                Re: What Floating-Point Precisions Would Physicists Prefer? Quadibloc <jsavard@ecn.ab.ca> - 2015-08-07 11:41 -0700
                Re: What Floating-Point Precisions Would Physicists Prefer? "hanson" <hanson@quick.net> - 2015-08-07 16:21 -0700
  Re: What Floating-Point Precisions Would Physicists Prefer? Timo <timo@physics.uq.edu.au> - 2015-08-05 04:47 -0700
    Re: What Floating-Point Precisions Would Physicists Prefer? Poutnik <Poutnik4NNTP@gmail.com> - 2015-08-05 14:36 +0200

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