Subject: 754r March meeting minutes
Date: Thu, 31 Mar 2005 20:17:49 -0800
From: "Kidder, Jeff" <jeff.kidder@intel.com>



[I don't seem to have the attendee list for day two. Suffice it here to
say it was well attended.]

* Vice-Chair opening
Jeff elected Vice-Chair to replace Alex Liu. Thanks to Alex for his
contributions.

* Min/Max discussion
Dan thinks the equality cases aren't a big deal in min/max.

Prof. Kahan summarizes as two applications of a selecting min/max
produce what the draft calls for, except it doesn't deal with +0, -0.
Some people definitely want to filter out NaNs (windowing).
Some people definitely want to get a NaN as an indication of trouble.
Have seen how to deal with -0 if min/max didn't. "It isn't a big thing"
Need to ask interval arithmetic community.
  If I have a tag I don't need -0 to make the distinction.
  With no tag the -0 semantics are important.
  Sun style intervals wants -0, but doesn't want to filter out NaN.

At issue: what is the default when you say "max(x,y)" in a language?

Uses:
Cuts: fluid flows, complex variables
Don't really care about the -0 treatment in min/max for this case.

AR: Roger can do the editing to do the mag and max functions.

AR: Roger to talk to the Russian interval arithmetic folks

AR: Roger post to 754r on the -0 question

Dan: if we could get around the "one little issue of +/-0" we could
treat this as an app note.

Roger: Our IPF compiler promote compare select to min/max (what about
invalid for a compare with NaN)

David: Sun does not have min/max instructions. Have conditional moves.

Eric: have fselect which uses compare.

Kahan: Architectures we have canvassed would prefer Roger's proposals.
If the interval arithmetic folks are happy with it.

If you are implementing the min/max routines you don't want the invalid
signal on NaNs.

Eric:
"Sounds like we are trying to change the definition to match existing
hardware.
If they are new why don't we just implement them the way we want them to
be and someday we will implement them correct. Who cares if HW at this
point can't do it"

Kahan:
If we make them only able to do lethargically it won't be done.

Jim:
Supporting +/- zero is slow on current HW.

Kahan:
Finding the largest element (or magnitude) happens a lot in my world.
Want that to be very fast.

Consensus:
Wait for answers from Roger.

Eric doesn't have problems with the "Option 3".

Dave:
We have some really fundamental problems around formats and expression
evaluation.

* Proposals proposal
Dan's proposal for new way of treating proposals and building the agenda
for meetings accepted without objection.

* Decimal
Kahan: in the long run I expect decimal to take over from binary.
For that we need interchange formats of specified widths.

What matters is there is a significant difference in SW implementations.
The SW has to be available in the public domain.

Conversion costs may dominate.

Ivan: comparisons will outweigh adds in databases

[Much other discussion that I was unable to capture]