N
Nick Maclaren
- Jan 1, 1970
- 0
|>
|> > |> IEEE achieved its objective a long time ago: just about all hardware
|> > |> and software uses it.
|> >
|> > That is a political objective, not a technical one; I was referring
|> > to a technical objective.
|>
|> I wouldn't call it political at all - the goals of standards are obvious and
|> non-political (the *process* of establishing a standard is often political,
|> but that is a different matter altogether).
The technical goals of standards are obvious? The mind boggles.
Clearly you haven't been involved with many of their committees.
|> > |> So that is not the problem. However it doesn't
|> > |> explicitly allow a subset of the features to be supported, which is what
|> > |> almost all implementations do.
|> >
|> > In different ways, which means that it hasn't even achieved its
|> > political objective in full.
|>
|> Well the main goal was to create a common binary format which gives
|> identical results on all implementations. That is exactly what we have
|> today, so it is an example of a standard that worked well.
That is factually false, as you yourself stated. Not merely are some
aspects of it left implementation-dependent, you yourself stated that
most implementations use hard underflow (actually, it's not that simple).
Also, you are ignoring the fact that almost all programs use languages
other than assembler nowadays, and the IEEE 754 model is notoriously
incompatible with the arithmetic models used by most programming
languages. That, in turn, means that two compilers (or even options)
on the same hardware usually give different results, and neither are
broken.
|> > |> Flushing denormals to zero is one key feature that is missing for example.
|> > |> Similarly round-to-even is the only rounding mode ever used. It would be
|> > |> easy to fix the standard to make the current defacto situation official.
|> >
|> > Which? I know of dozens of variants.
|>
|> I know a compiler that supports 5 variants, but there aren't any useful
|> variants beyond that. Even that is too much, I think just 1 or 2 commonly
|> used subsets would be sufficient to capture 99% of implementations.
There are a lot more than five variants in use today, even just at
the hardware level. Actually, Intel has at least three, and quite
likely more.
Regards,
Nick Maclaren.
|> > |> IEEE achieved its objective a long time ago: just about all hardware
|> > |> and software uses it.
|> >
|> > That is a political objective, not a technical one; I was referring
|> > to a technical objective.
|>
|> I wouldn't call it political at all - the goals of standards are obvious and
|> non-political (the *process* of establishing a standard is often political,
|> but that is a different matter altogether).
The technical goals of standards are obvious? The mind boggles.
Clearly you haven't been involved with many of their committees.
|> > |> So that is not the problem. However it doesn't
|> > |> explicitly allow a subset of the features to be supported, which is what
|> > |> almost all implementations do.
|> >
|> > In different ways, which means that it hasn't even achieved its
|> > political objective in full.
|>
|> Well the main goal was to create a common binary format which gives
|> identical results on all implementations. That is exactly what we have
|> today, so it is an example of a standard that worked well.
That is factually false, as you yourself stated. Not merely are some
aspects of it left implementation-dependent, you yourself stated that
most implementations use hard underflow (actually, it's not that simple).
Also, you are ignoring the fact that almost all programs use languages
other than assembler nowadays, and the IEEE 754 model is notoriously
incompatible with the arithmetic models used by most programming
languages. That, in turn, means that two compilers (or even options)
on the same hardware usually give different results, and neither are
broken.
|> > |> Flushing denormals to zero is one key feature that is missing for example.
|> > |> Similarly round-to-even is the only rounding mode ever used. It would be
|> > |> easy to fix the standard to make the current defacto situation official.
|> >
|> > Which? I know of dozens of variants.
|>
|> I know a compiler that supports 5 variants, but there aren't any useful
|> variants beyond that. Even that is too much, I think just 1 or 2 commonly
|> used subsets would be sufficient to capture 99% of implementations.
There are a lot more than five variants in use today, even just at
the hardware level. Actually, Intel has at least three, and quite
likely more.
Regards,
Nick Maclaren.