Re: [lmi] Contemplating the infinite

[Vadim Zeitlin]

On Fri, 25 Jun 2010 01:26:49 +0000 Greg Chicares <address@hidden> wrote:

GC> Other occurrences of DBL_MAX and std::numeric_limits<double>::max() (which
GC> means the same thing) remain in HEAD. I'm not going to consider changing
GC> them now if they aren't directly related to xml, product files, or the GUI,
GC> particularly in light of this article
GC>   http://www.cygnus-software.com/papers/x86andinfinity.html
GC> that cautions about performance problems.

 This is definitely an interesting link, I had no idea there could be such
a huge slowdown when operating with infinities or NANs on x87. However the
article also says that SSE unit doesn't suffer from this penalty at all so
this could be another reason to switch to using it as discussed before.

 It seems that SSE is generally more predictable than x87, probably because
it doesn't have any backwards compatibility concerns going 30 years back to
care of. And increased precision of x87 (which can cause hard to understand
problems because of the use of different formats for storage of doubles and
FPU registers) aside, this seems to be a good enough reason to prefer SSE
even in spite of the possible performance gains.

 Regards,
VZ