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From: azimmer@rsa.hisd.harris.com (Alan D Zimmerman)
Newsgroups: comp.lang.ada
Subject: Re: Rational/Verdix Number Bug
Message-ID: <3il66m$ps1@jabba.ess.harris.com>
Date: 24 Feb 95 17:49:10 GMT
References: <3i0nip$b55@rational.rational.com>
Reply-To: azimmer@rsa.hisd.harris.com
Organization: Loral Space & Range Systems
NNTP-Posting-Host: appsrv2.rsa.hisd.harris.com
Date: 1995-02-24T17:49:10+00:00
List-Id: <comp.lang.ada>

In article <3i0nip$b55@rational.rational.com>, kdm@rational.com (Kent Mitchell) writes:
> Roger C Hennesen (rch@odo.amherst.com) wrote:
> : We have discovered that the number 2147.483648 is not handled properly by the
> : Sun/Rational/Verdix Ada compiler. Multiplying or dividing by this number
> : results in a sign inversion in the result.
> 
> : The position of the decimal point does not matter. The number is 2^31. Also
> : numbers around this number (e.g. +/- 0.000003) exhibit strange results in 
> : floating point calculations.
> 
> : The problem was discovered in SunAda version 2.1.1 and duplicated with the SCO
> : Verdix Compiler version 6.2.1.
> 
> : Rational was notified of the problem, but has not responded.
> 
> O.K. I'll respond here since I'm concerned about both the bug *and* the
> statement that we didn't respond.
> First WRT the "no response" issue, hHow did you report the bug (phone,
> e-mail, or?).  Did you get *no* response (not even a customer support "log"
> number or automated e-mail response) or ???.
> 
> Second WRT the bug, do you have a minimum faulty program which reproduces
> the problem?  If so mail it to me so I can take a look at is and reproduce
> the problem internally.  I'll see if I can't grease the skids a bit.
> 
> --
> Kent Mitchell                   | One possible reason that things aren't
> Technical Consultant            | going according to plan is .....
> Rational Software Corporation   | that there never *was* a plan!

Well, I am in a perplexing situation.  I tried this when I first heard
about the problem and duplicated it with a program like the one attached.
I just tried it and  I could not duplicate it.  I am running SunAda 1.1(j)
on a SPARC LX.  Below is the test program.

with text_io;
procedure test_float is
  test : float := 2147.486348;
  package flt_io is new text_io.float_io(float);
begin
  flt_io.put(test);
  text_io.new_line;
  flt_io.put(test * 2.0);
  text_io.new_line;
  flt_io.put(test / 2.0);
end test_float;

Here are my results:

2.14748634800000E+03
 4.29497269600000E+03
 1.07374317400000E+03

Alan

-- 
|        Alan D. Zimmerman        | Eagle Scout                     |
|   azimmer@rsa.hisd.harris.com   | Scoutmaster T324                |
|-------------------------------------------------------------------|
|     All opinions are solely my own and do not represent Loral     |
|                   On My Honor I will do my best...                |