On Thu, Apr 13, 2006 at 04:24:45PM +0100, Simon Marlow wrote:
- get an implementation of this in GHC which computes the same results for all platforms?
I would certainly hope so, if we can find the source of the discrepancy and devise a fix.
I'd just point out that C compilers don't allow you to get the same results on all platforms, and doing so in general requires slow floating point arithmetic, mostly because there don't seem to be any platforms in production that implement IEEE arithmetic. I wouldn't like the standard (or compiler) to enforce special checks every time we do floating point arithmetic. It would be nice, perhaps, as an option, but that would (as I understand it) be considerable effort and a considerable slowdown, for relatively little benefit, which is why gcc hasn't bothered with it either. I imagine that if producing reproducible arithmetic is beyond the means of the gcc development team, it's also beyond that of the ghc development team, especially since you can always get reproducible arithmetic (I presume) by using Rationals. -- David Roundy