I also thought: "great explanation" and nodded sagely when I read this.
However, consider this code:
NUL = ''
CM = ','
A = -409071.8775: CM: 475000: CM: -652413: CM: 652413: CM: -475000: CM:
409071.8775
*
*
TEST.VMC = 1
TEST.TOTAL = 0
*
LOOP UNTIL FIELD(A, CM, TEST.VMC) = NUL DO
TEST.TOTAL += FIELD(A, CM, TEST.VMC)
TEST.VMC += 1
REPEAT
*
IF TEST.TOTAL = 0 THEN
PRINT 'OK'
END ELSE
PRINT TEST.TOTAL, (TEST.TOTAL = 0), TEST.TOTAL - 0, (OCONV(TEST.TOTAL,
'MD0') = 0)
END
Running this on our Universe system 11.1.1 produces:
0 0 0 1
So, in other words zero is the total result in TEST.TOTAL but this does not
equate to zero.
Now I know I can get round this by rounding the answer but am not sure why I
should have to. Any ideas?
Thanks
Brett
"Martin Phillips"
<martinphill...@ladybridge.com<mailto:martinphill...@ladybridge.com>> wrote in
message
news:<2636297EDC484501AD1A5AC277EE76A7@lbs8<news:%3c2636297EDC484501AD1A5AC277EE76A7@lbs8>>...
> 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<mailto:zhamme...@hubert.com>>
> To: <u2-users@listserver.u2ug.org<mailto: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<mailto:zhammerle@hubertREMOVE_THIS.com>
>
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