> On Wed, Dec 09, 1998 at 05:58:39PM +0000, Thomas G. Lockhart wrote:
> > In my limited testing, the only variable was the compiler. I did not
> > change the C library. So, one can point fingers at the compiler for not
> > behaving the same as the old compiler, or one can surmise that there is
> > a deeper story of older C library misbehavior which was covered up by
> > the older compiler in a great conspiracy. I leaned toward blaming the
> > compiler, on the assumption that for most simple math compilers probably
> > generate inline code rather than going to a library. It may be that for
> > any compiler at high optimization levels you tend to see rounding
> > problems since they don't bother cleaning up results.
>
> FWIW, I understand this to be a problem mostly on the x86 architecture,
> where the floating point registers have higher precision than memory
> storage. Thus the results are somewhat unpredictable, depending on whether
> registers are spilled into memory. The -ffloat-store will help with
> explictly named variables, but not temporary intermediate results.
Yes 80-bits vs. 64-bits. If the computation hits memory, you loose
precision. A definate problem, and compiler-specific.
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