[Info-vax] Roadmap

[gezelter at rlgsc.com]

On Saturday, January 5, 2019 at 9:19:06 PM UTC-5, Arne Vajhøj wrote:
> On 1/5/2019 8:23 PM, Dave Froble wrote:
> > On 1/5/2019 1:48 PM, John Reagan wrote:
> >>        The format of the REAL_SIZE qualifier is as follows:
> >>
> >>           /REAL_SIZE={SINGLE}
> >>                      {DOUBLE}
> >>                      {GFLOAT}
> >>                      {SFLOAT}
> >>                      {TFLOAT}
> >>                      {XFLOAT}
> 
> >> So Dave's "OPTION SIZE = ( INTEGER WORD , REAL DOUBLE )" which was 
> >> originally used to say "I want extra precision on my REALs" locks into 
> >> you Dfloat on Itanium.
> 
> >> What a horrible design decision.  So people who didn't say anything on 
> >> Itanium, get fast Sfloat but the moment you want more precision and 
> >> blindly say "REAL DOUBLE", you get your extra precision (but no extra 
> >> range) and a performance hit.
> 
> > Maybe the D_FLOAT isn't so bad, if you're not doing a lot of work with it.
> 
> Basic is probably not a favorite language for number crunchers, so
> most likely the practical impact is minimal.
> 
> It is possible though to create an example showing a difference:
> 
> $ type dbl.bas
>          option type = explicit
>          declare long constant n = 10000000
>          external long function pas$clock2
>          dim real x(n)
>          declare long j, i, t1, t2
>          t1 = pas$clock2()
>          for j = 1 to 10
>            x(1) = 1.0
>            for i = 2 to n
>              x(i) = (x(i - 1) * 2 + 2) / 2
>            next i
>          next j
>          t2 = pas$clock2()
>          print using "#### (##########.#)"; (t2 - t1); x(n)
>          end
> $ bas/real=double dbl
> $ lin dbl
> $ r dbl
> 5810 (  10000000.0)
> $ bas/real=tfloat dbl
> $ lin dbl
> $ r dbl
> 3000 (  10000000.0)
> 
> (forgive me for any basic Basic blunders - it is not a language
> I am using)
> 
> Arne

Arne,

BASIC is still popular in some quarters, where it is used for serious systems. I have had more than a few clients who meet this description.

In many ways, interoperability of one form or another is the most important use of the different formats. Some have historical data files. Some have mixed-architecture OpenVMS clusters. Others exchange binary data with other systems, on the same or different machine, of the same or different organization.

OpenVMS standards also mean that these differences can arise due to different parts of the same software image being written in different languages.

It is thus not a debate of "which is better", but a debate of "which is needed". This situation argues for provision of both defaults (e.g., compiler switches, implicit declarations) and explicit data types, as well as the obvious cross-type conversions.

- Bob Gezelter, http://www.rlgsc.com