But you need to look at the bias for the exponent. Both views would be encoded the same. I guess I didn't explain this very well before but this example will help. For the short format, there are 7 significant digits. For the LUV, bias of the exponent is 95. For the RUV, bias of the exponent is 101. See this in figure 20-2 that we mentioned before.
Also, I think we're getting cohorts mixed up with LUV/RUV. What you're showing below are two different members of a cohort. Not too different views of the same representation. But that's another story. I think you'll see what I mean below. Let's take the number 7. This can be encoded with the LUV as 7.000000 x 10**0 or as 7000000. x 10**-6. In both cases the significand is represented the exact same as 7000000. For LUV, the decimal point is implied to the right of the seven. For RUV, the implied decimal is to the right of the rightmost zero. For LUV, the unbiased exponent is 95 since 95 - 95 = 0. For RUV, the unbiased exponent is 95 since 95 - 101 = -6. So in BOTH cases, the unbiased exponent (which is what is encoded in the representation in memory) is 95. And in both cases the significand is encoded as 7000000. The representation in memory is the SAME. It's just a matter of whether you want to look at as 7.000000 x 10 * (95-95) -or- 7000000 x 10 * (95-101) I hope this example helps. Take care, Gary -----Original Message----- From: IBM Mainframe Assembler List <[email protected]> On Behalf Of Abe Kornelis Sent: Tuesday, March 5, 2024 8:58 AM To: [email protected] Subject: Re: Decimal Floating Point Numbers Hi Peter, thanks for your response. Nice to hear from you :-) They would be encoded quite differently. Say you'd encode the value seven. In LUV this would be 7.00000*10**0 In RUV this would be 000007*10**0 In either case the number of zero digits would depend on the format of the DFP: D/E/X For the sake of completeness: In LUV the digit 7 would go into the combination field In RUV the digit would be at the end of the significand. Unless I am quite mistaken, which is still quite conceivable :-( Kind regards, Abe === Op 05/03/2024 om 15:19 schreef Peter Relson: > I am imagining (and could easily be wrong) that the hex data is identical > across the views (and thus the instruction implementation does not care about > the view), and it's only a question of which bits you choose to look at (or > what arithmetic logical manipulation you use) if formatting the value for > human consumption. > > For example, the exponent differs, as does the significand (a term I had not > known of until seeing it in the POp). > > I don't know what kind of dump was being looked at, but perhaps there's a > formatting option within the dump viewing program that might say "show me > this as a Right-Unit View DFP value". > > Peter Relson > z/OS Core Technology Design
