On Tue, 01 Apr 2008 19:29:05 -0300 Clark F Morris
<cfmpublic@[EMAIL PROTECTED]
>
wrote:
:>On Tue, 1 Apr 2008 13:14:46 -0600, "Frank Swarbrick"
:><Frank.Swarbrick@[EMAIL PROTECTED]
> wrote:
:>>>>> On 4/1/2008 at 12:43 PM, in message
:>><if05v3503beg04nonbeci3n8eqo2vill79@[EMAIL PROTECTED]
>, Clark F
:>>Morris<cfmpublic@[EMAIL PROTECTED]
> wrote:
:>>> On Mon, 31 Mar 2008 22:37:12 -0600, Robert <no@[EMAIL PROTECTED]
> wrote:
:>>>>On Mon, 31 Mar 2008 21:55:10 -0300, Clark F Morris
:>>><cfmpublic@[EMAIL PROTECTED]
> wrote:
:>>>>>On Tue, 18 Mar 2008 19:34:51 -0600, Robert <no@[EMAIL PROTECTED]
> wrote:
:>>>>>>Lots of muddled thinking on numeric errors has been published. Some
talk
:>>> about 'binary
:>>>>>>arithmetic' without making a distinction between integer and
floating
:>>> point. Here's an
:>>>>>>example:
:>>>>>Try doing a simple divide like calculate the value of 1 / 5 in
binary.
:>>>>OK.
:>>>>01 numerator value 1 binary pic 9(9).
:>>>>01 denominator value 5 binary pic 9(9).
:>>>>01 quotient binary pic 9(9)v9(4).
:>>>>compute quotient = numerator / denominator
:>>>>display quotient
:>>>>0000000002000
:>>>>>You get a never ending fraction.
:>>>>Looks pretty diadic to me.
:>>> You may have to do this in Assembler to get the results that I am
:>>> talking about. Take a look at the generated instructions. If I had
:>>> access to an IBM mainframe I would compile a small test program to
see
:>>> what the underlying code is.
:>>5820 9510 L 2,1296(0,9) NUMERATOR
:>>4E20 D1C4 CVD 2,452(0,13) TS2=4
:>>D203 D1C0 C02A MVC 448(4,13),42(12) TS2=0
:>> SYSLIT AT +42
:>>F060 D1C5 0004 SRP 453(7,13),4(0),0 TS2=5
:>>5820 9518 L 2,1304(0,9) DENOMINATOR
:>>4E20 D1D0 CVD 2,464(0,13) TS2=16
:>>FDB4 D1C0 D1D3 DP 448(12,13),467(5,13) TS2=0
:>> TS2=19
:>>F896 D1E0 D1C0 ZAP 480(10,13),448(7,13) TS2=32
:>> TS2=0
:>>960F D1E9 OI 489(13),X'0F' TS2=41
:>>D202 D1D8 C02A MVC 472(3,13),42(12) TS2=24
:>> SYSLIT AT +42
:>>D204 D1DB D1E5 MVC 475(5,13),485(13) TS2=27
:>> TS2=37
:>>4F20 D1D8 CVB 2,472(0,13) TS2=24
:>>F144 D1DB D1E0 MVO 475(5,13),480(5,13) TS2=27
:>> TS2=32
:>>4F50 D1D8 CVB 5,472(0,13) TS2=24
:>>5C40 C004 M 4,4(0,12) SYSLIT AT +4
:>>1E52 ALR 5,2
:>>58B0 C034 L 11,52(0,12) PBL=1
:>>47C0 B698 BC 12,1688(0,11) GN=16(000A70)
:>>5A40 C000 A 4,0(0,12) SYSLIT AT +0
:>> GN=16 EQU *
:>>1222 LTR 2,2
:>>47B0 B6A2 BC 11,1698(0,11) GN=17(000A7A)
:>>5B40 C000 S 4,0(0,12) SYSLIT AT +0
:>> GN=17 EQU *
:>>9045 9520 STM 4,5,1312(9) QUOTIENT
:>Wow, they are actually doing this in decimal. I wonder what the code
:>would be like using binary instructions. I see they are handling the
:>remainder separately.
I would guess the conversions are being done to properly handle the
different
scaling factors, where decimal arithmetic can handle larger precisions
(fullword is limited to 10 digits while packed can hold 15 digits - and
with Z
hardware, the numbers double).
Try them all with the same picture, 9(4)V4(9), which will fit in a word.
--
Binyamin Dissen <bdissen@[EMAIL PROTECTED]
>
http://www.dissensoftware.com
Director, Dissen Software, Bar & Grill - Israel
Should you use the mailblocks package and expect a response from me,
you should preauthorize the dissensoftware.com domain.
I very rarely bother responding to challenge/response systems,
especially those from irresponsible companies.
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