What is acceptable for -ffast-math? A numerical viewpoint

[Ross Smith]

dewar@gnat.com wrote:
> 
> <<Speaking as someone with an interest in games programming, I would
> _love_ to have an option that tells GCC "apply any transform that would
> make sense for true real numbers, and to hell with the last few decimal
> places".
> >>
> 
> Please reread my previous example. The trouble is that "apply any transform
> that would make sense for true real numbers" does not just affect "the last
> few decimal places", it can have much more radical effects, such as making
> all your programs die immediately with overflow errors even if your numbers
> are nowhere near the limit of overflow in the canonical evaluation semantics.

You'll have to show me a _realistic_ example before I'll believe that. I
don't consider anything involving the likes of DBL_MAX or 10**1000 to be
realistic.

-- 
Ross Smith <ross.s@ihug.co.nz> The Internet Group, Auckland, New Zealand
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"Unix has always lurked provocatively in the background of the operating
system wars, like the Russian Army."                  -- Neal Stephenson