Re: m68k gcl/maxima: Minor Floating point errors
Greetings!
Rick Younie <rick@def.debian.net> writes:
> Camm Maguire wrote:
> > Greetings! I have one Debian machine (m68k) which is producing very
> > small numerical discrepancies on the results of the two floating point
> > intensive tests in rtest8.mac:
>
> Hi,
>
> That rang a bell. There's this in the gcc man page:
>
> -ffloat-store
> Do not store floating point variables in registers. This pre-
> vents undesirable excess precision on machines such as the 68000
> where the floating registers (of the 68881) keep more precision
> than a double is supposed to have.
>
> For most programs, the excess precision does only good, but a
> few programs rely on the precise definition of IEEE floating
> point. Use `-ffloat-store' for such programs.
That did it -- thanks! As Richard Fateman observed, its quite
surprising the magnitude of the difference was so large. Apparently
m68k has the more accurate answer, right? In any case, I'm adding
-ffloat-store to gcl's compile flags on m68k to avoid testing
problems.
Take care,
>
> Rick
> --
>
>
--
Camm Maguire camm@enhanced.com
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