On 10/2/10 7:00 PM, Jeremy Drake wrote:
On Sat, 2 Oct 2010, James McKenzie wrote:
Looks like you got 'bit' by the way that a finite storage method mangles
floating information. There was a lengthy discussion on how to 'overcome'
this on the Wine-Development list a short while ago.
No, those tests aleady account for that.
/* When comparing floating point values we cannot expect an exact match
* because the rounding errors depend on the exact algorithm.
*/
#define EQ_DOUBLE(a,b) (fabs((a)-(b)) / (1.0+fabs(a)+fabs(b))< 1e-14)
#define EQ_FLOAT(a,b) (fabs((a)-(b)) / (1.0+fabs(a)+fabs(b))< 1e-7)
ok_(__FILE__,line)(r == res&& (FAILED(r) || EQ_DOUBLE(out, dt)),
"expected %x, %.16g, got %x, %.16g\n", r, dt, res,
out);
My understanding is that that algorithm should work to account for
floating-point inaccuracies (though technically should be using
DBL_EPSILON and FLT_EPSILON instead of 1e-X constants, but they're
probably not portable enough for this project),
I was simply bit by my own stupidity, not running my last changes against
a Windows OS before sending my patch. This has been corrected in my try2.
Ok. I seen that. However, will this work in Wine as well might come up
as it has before.
I don't want to raise the 'noise' level and I did not see [try 2] before
making my comment, but this might be something you want to keep in mind
for the future.
Also, please be aware that my comment is based on a previous thread,
which you still might want to visit, in this mailing list/forum. It may
save you time and give you something to think about in regards to this
patch and future patches.
Note: My comment is not based on actual programming experience using
the Epsilon features and code, but rather on previous comments. I'm
just a simple programmer who tests Wine on the Mac platform.
Since I tend to remove messages as they no longer apply to my personal
habits, however I did find a pointer to the following document written
by Bruce Dawson:
http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm
This came from
http://www.winehq.org/pipermail/wine-devel/2010-July/085089.html
It looks like you read through it, based on a review of the proposed
patch. I don't know if this can be applied to the ok() checks though.
James McKenzie
