comparing floating points via "==" or "!="
Ian Smith
smithi at nimnet.asn.au
Fri Dec 2 03:55:49 UTC 2011
On Thu, 1 Dec 2011, Alexander Best wrote:
> On Wed Nov 30 11, Igor Mozolevsky wrote:
> > On 30 November 2011 22:44, Alexander Best <arundel at freebsd.org> wrote:
> >
> > > i played a bit with the gcc -Wfloat-equal warning and noticed that inside
> > > sys/dev/ath/ath_rate/sample/tx_schedules.h, a lot of comparisons of floating
> > > points are happening ("=="). is there a better way to deal with this?
> >
> > as opposed to (abs(a-b) < tolerance)?
>
> fabs(3) actually, or some other way, e.g. described in:
>
> http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm
Bookmarked, thanks. Very good article, and I never knew IEEE floats
could be compared as integers! OT for wireless, but very useful for
some astronomical stuff I'm working on .. in Pascal, no less :)
cheers, Ian
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