Rounding errors using doubles?

[craig@jcb-sc.com]

>Both compilers have options to force pure 64-bit arithmetic (53-bit
>precision) throughout (at some cost in speed): -ffloat-store on EGCS,
>/Op on MSVC.

Take -ffloat-store off that list: it doesn't do the above.  It affects
only explicit *stores* to *variables*, not intermediate coputations.  egcs
provides no way to force 64-bit FP arithmetic.  In fact, I'd be surprised
if -ffloat-store "improved" the behavior of the (buggy) program originally
submitted in this thread.

Other than that, thanks for the decent explanation -- if this isn't
in the FAQ, it should be, and if it is, we should refrain from
repeating it, and point people there instead!

        tq vm, (burley)