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P1788, Arnold,Please note in your message below: "apparently", "I haven't yet had the time to read through the 754 documentation...", "if it is...", "if it is not..." etc. There is NOTHING that sounds certain about any of that.
It also doesn't inspire confidence in me that you have studied how such changes would impact the design of existing and/or future hardware circuits and semiconductors. Where is your detailed anaylsys of that? I also have much skepticism DirectedInf will work when it comes to interval comparisons, since it appears the comparisons will require some decoration, anyways, in order that they should give the correct results. So there is much uknown, and even plenty to doubt. Therefore it is a research project as well.
Stepping back to take a broader view of things, I'd point out that as it pertains to P1788 I don't agree with Arnolds recent comments. For example, by the standards of:
And it is unwise to account for things that still need research to find out how to do it well. The right placce to consider these is when a standard is upgraded and the relevant information is then available.
many of the P1788 motions which have already been investigated and accepted should never have even been put forth on the table or considered. This is particularly true (and continues to be so) about all motions regarding decorations, and arguably even Motion 5, which requires a controversial hardware operation Infinity*0=0 which currently has no precedent in the world of floating-point semiconductor design.
I believe that the scientific process is to study all the variables relevant to the question at hand, so that conclusive and informed decisions can be made about what is the best solution or decision to make going forward. For P1788, this means taking time to consider the impact of including Overflow in the standard.
I wouldn't object to looking at DirectedInf, either, so long as it is also decided to study Overflow such that a comparision between the two can be made.
To not do so, in my view, would be ad-hoc and subjective at best, if not simply a totally hasty rush to an uninformed judgement. I don't see that would be a very scientific way to build a standard, nor that it would be beneficial to P1788.
Nate----- Original Message ----- From: "Arnold Neumaier" <Arnold.Neumaier@xxxxxxxxxxxx>
To: "Nate Hayes" <nh@xxxxxxxxxxxxxxxxx> Cc: <rbk@xxxxxxxxxxxxx>; "1788" <stds-1788@xxxxxxxxxxxxxxxxx> Sent: Wednesday, September 29, 2010 10:02 AM Subject: Re: Overflow and Inf
Nate Hayes wrote:I suppose that also eliminates any consideration that P1788 should include or investigate further the "DirectedInf" mechanism in the Vienna Proposal.I don't understand. DirectedInf is simply the inf with the interpretation as in the last section of the Vienna proposal,fully settled there. The only new thing emanating from the recent discussion is that it apparently can be implemented as a nonstandard Inf without violating 754 rules. I haven't yet had the time to read through the 754 documentation to find out whether this is indeed so. If it is, nothing else needs to be researched about it. If it is not, then we cannot make use of DirectedInf in a 754 context.(Neither can one use Overflow, which propagates the same way as DirectedInfbut has a more complex semantics that conflicts withMotion 3.)On 9/29/2010 08:56, Arnold Neumaier wrote:Ralph Baker Kearfott wrote:On 9/26/2010 12:25, Arnold Neumaier wrote:A standard should be as restrictive as possible, given the constraint that it does not exclude something that has been useful in the past.Again, are we taking care not to stifle innovation? What about things that will be useful but we haven't discovered yet? In any case, is the above statement standing on its own relevant to us?It is impossible to account for things not ywet discovered. And it is unwise to account for things that still need research to find out how to do it well. The right placce to consider these is when a standard is upgraded and the relevant information is then available.