Re: Moving VAX into 21 century :-)

[Anders Magnusson <ragge%ludd.ltu.se@localhost>]

Den 2019-08-26 kl. 17:38, skrev Paul Koning:
> > On Aug 26, 2019, at 10:39 AM, Anders Magnusson <ragge%ludd.ltu.se@localhost> wrote:
> >
> > Den 2019-08-26 kl. 15:56, skrev Paul Koning:
> > > > ...
> > > I don't get it.  VAX float is what the hardware uses.  IEEE float is different in many details.  For example, VAX doesn't have subnormals since all numbers are normalized and the MSB is not represented in the encoding.  So while VAX F might have the same field layout as IEEE single precision, they are in fact completely different data types.
> > >
> > > Why would you want to slow things down by emulating an alien float format?
> > Because having a non-IEEE format leads into more and more trouble since noone cares about vax anymore.
> > Try to compile almost anything that uses floating point these days, you get into trouble with lacking INF and NAN (or the small exponent that D-float has).  Or things failing during run-time; not fun to search for.
> VAX does have NaN, but not Inf or denormal.  I can't see why real float applications have a need for Inf, though.
Well, not really NaN, but a floating point fault will be generated. 
Handling SIGFPE from a user application is quite uncommon these days, 
you get a core file instead which is not what you want when running a 
program just because it uses floating point.

-- R