From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: *
X-Spam-Status: No, score=1.3 required=5.0 tests=BAYES_00,INVALID_MSGID,
	MSGID_RANDY autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,3f2ed3f93fdb688b,start
X-Google-Attributes: gid103376,public
From: David W. Glessner <david_glessner@my-deja.com>
Subject: Assignment of small Float values
Date: 2000/04/17
Message-ID: <8dfm0q$8nr$1@nnrp1.deja.com>#1/1
X-Deja-AN: 612334093
X-Http-Proxy: 1.0 x25.deja.com:80 (Squid/1.1.22) for client 205.175.225.5
Organization: Deja.com - Before you buy.
X-Article-Creation-Date: Mon Apr 17 18:43:43 2000 GMT
X-MyDeja-Info: XMYDJUIDdavid_glessner
Newsgroups: comp.lang.ada
X-Http-User-Agent: Mozilla/4.51 [en]C-CCK-MCD (Win95; U)
Date: 2000-04-17T00:00:00+00:00
List-Id: <comp.lang.ada>

Why does GNAT treat the non-zero constant as 0.0 in the assignment to
F1 in the following example?  32-bit IEEE floating-point should
support values down to around 10**-38 (and even down to 10**-45 or
so for subnormal numbers).

Note that Rational Apex Ada behaves as I expected.

Is there something in Ada that allows the assignment of 0.0 or is
this a GNAT bug?


-- Test program that shows unexplained (to me at least) GNAT behavior
for
-- floating point assignments.
--
-- GNAT 3.12p Win98 displays:
-- 0.00000E+00                           <-- Why does GNAT display 0.0?
-- 6.66666666666667E-33
-- 6.66667E-33
--
-- Rational Apex 3.0.0b for Solaris (Sparc) displays:
-- 6.66667E-33
-- 6.66666666666667E-33
-- 6.66667E-33
with Ada.Text_Io;
procedure Test_Float_Range is
    C : constant := 6.6666666666666666E-33;
    F1 : Float := C;
    F2 : Long_Float := C;
    F3 : Float := Float (F2);
    use Ada.Text_Io;
begin
    Put_Line (Float'Image (F1));
    Put_Line (Long_Float'Image (F2));
    Put_Line (Float'Image (F3));
end Test_Float_Range;


Sent via Deja.com http://www.deja.com/
Before you buy.