You didn't read Martin's answer, or did you?
So to what value is WIDEZERO set on your UV system?
On 29/09/2011 16:40, Oaks, Harold wrote:
Running Martin's code on a Universe system, got:
(A+B) = C? YOU ROCK
A = 4096.9, B = 106.19, (A+B) = 4203.09, C = 4203.09
Interesting - Universe does better than Unidata at this particular task.
Harold Oaks
Clark County
-----Original Message-----
From: u2-users-boun...@listserver.u2ug.org
[mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Brian Leach
Sent: Thursday, September 29, 2011 6:21 AM
To: 'U2 Users List'
Subject: Re: [U2] The math just doesn't work.
And just to add to Martin's excellent answer - the normal workround for
any
computer system is to use integral values, scaling and descaling as
required.
In case you think this is a U2 specific limitation, here's the same in
C# as
a console app -
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
float A = 3176.79f;
float B = 106.19f;
float C = 3282.98f;
float D = 920.11f;
A = A + D;
C = C + D ;
if((A+B) != C ){
Console.WriteLine("You lie, A+B = {0}, C= {1}",(A+B), C);
} else{
Console.WriteLine("you rock");
}
pressAnyKey();
}
static void pressAnyKey()
{
Console.Write("Press any key ...");
Console.ReadLine();
}
}
}
Result -
You lie, A+B = 4203.09, C= 4203.09
-----Original Message-----
From: u2-users-boun...@listserver.u2ug.org
[mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Martin
Phillips
Sent: 29 September 2011 13:46
To: U2 Users List
Subject: Re: [U2] The math just doesn't work.
Hi George,
As a general rule in programming, comparison of floating point values
for
equality should be avoided. This is because, just as we cannot write the
number one third accurately in decimal notation, so the IEEE floating
point
format used by computer systems cannot store numbers accurately. The
example
that I use when teaching training courses is 14.2 which actually ends up
as
something close to 14.19999999997.
UniVerse gets around this with a wonderful concept called "wide zero"
that
says, when testing for equality of floating point numbers, they must be
within some specified value of being equal rather than strictly equal.
The
default wide zero error tolerance, set in IEEE format with the WIDEZERO
configuration parameter, is 2.91 * 10^-11 (2^ 035) which is good for
most
business applications but occasionally needs adjusting.
Unidata has a command, SET.WIDEZERO, to serve the same purpose but
defaults
to 0.0 for backward comaptibility.
Martin Phillips
Ladybridge Systems Ltd
17b Coldstream Lane, Hardingstone, Northampton NN4 6DB, England
+44 (0)1604-709200
----- Original Message -----
From: "George Hammerle"<zhamme...@hubert.com>
To:<u2-users@listserver.u2ug.org>
Sent: Thursday, September 29, 2011 1:30 PM
Subject: [U2] The math just doesn't work.
Can anybody please help?
For some reason A + B does not equal C in the comparison below. Is
there
any trick to get the comparisons to work properly?
Unidata 7.2 on Hp Unix 11+
Top of "TEST.COMP" in "RMH.MAIN", 13 lines, 263 characters.
*--: P
001: A = 3176.79
002: B = 106.19
003: C = 3282.98
004: D = 920.11
005: A = A + D
006: C = C + D
007: IF (A+B) # C THEN
008: CRT '(A+B) # C? YOU LIE'
009: CRT 'A = ':A:', B = ':B:', (A+B) = ':(A+B):', C = ':C
010: END ELSE
011: CRT '(A+B) = C? YOU ROCK'
012: CRT 'A = ':A:', B = ':B:', (A+B) = ':(A+B):', C = ':C
013: END
Bottom.
*--: FIBR
Filed "TEST.COMP" in file "RMH.MAIN" unchanged.
Compiling Unibasic: /db1/ud1/PGM/RMH.MAIN/TEST.COMP in mode 'u'.
compilation finished
(A+B) # C? YOU LIE
A = 4096.9, B = 106.19, (A+B) = 4203.09, C = 4203.09
George Hammerle
Programming Dude
Hubert Company LLC.
9555 Dry Fork Road
Harrison, Ohio 45030
513-367-8974
zhammerle@hubertREMOVE_THIS.com
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