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From: bwburnsed@aol.com (BWBurnsed)
Subject: Re: Can compilers do this?
Date: 1996/02/26
Message-ID: <4gtpsr$c9f@newsbf02.news.aol.com>#1/1
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sender: root@newsbf02.news.aol.com
references: <EACHUS.96Feb26114315@spectre.mitre.org>
organization: America Online, Inc. (1-800-827-6364)
newsgroups: comp.lang.ada
Date: 1996-02-26T00:00:00+00:00
List-Id: <comp.lang.ada>

I have read with interest the replies to my message. I can see that we
shall have to check with our specific vendor to know whether or not
this (validated!) compiler suffers from the  signed zero syndrome.
The discussion of "clipping" near zero is very interesting. Allow me to
elaborate (so to speak) on more of the surrounding code. Actually, they
provided a function (which I shall refer to as "clip") that was
implemented
thus (only the names have been changed, to protect the...):

  function Clip ( x : some_float_type;
                  Z : some_float_type )
     return some_float_type is
  begin
     if abs(x) <= Z then
        return 0.0;
     else
        return x;
     end if;
  end;

But-- when it came to employing this function, it goes something like:

  tmp_x : some_float_type;
  abs_x : some_float_type;
    ...
  tmp_x := {some calculation} ;
  abs_x := clip ( abs(tmp_x), 0.01 );

  if tmp_x * abs_x < 0.0 then
    final_answer := tmp_x;
  else
    final_answer := -tmp_x;
  end if;

There are also examples of simply using

  if X * abs(X) < 0.0 then..

but the above astounds me more.