[Info-vax] Roadmap

[Arne Vajhøj]

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