Re: Strange result with exponents... -- RPG400-L

On Friday, February 20, 2004, at 10:59 AM, Joe Pluta wrote:

Rremember, a lot of us dinosaurs don't have the benefit of a CS degree,
since when we were coming up there was no such thing.

Well I don't have a CS degree nor a Maths degree but I know about floating-point numbers so I think your argument is specious.

In fact, the only saving grace for this is that there is a note in the documentation that says floating point is used. It would be nice to see a warning that the use of this opcode effectively limits your precision;

Possibly but the input to most technical documents comes from the technicians. If something is blindingly obvious to you it takes a bit of effort to realise that maybe you should point that out to someone else. I don't blame IBM for this. I think part of a programmer's job is to be familiar with some things outside their usual realm. When Floats were added to RPG it would be reasonable to expect a bit of investigation about what they were and whether they would be useful but it seems most RPG programmers stayed with what they learned in RPG II hence all the confusion about B versus I data types.

it's way beyond the pale to expect an RPG programmer to know the
precision limits of FP arithmetic.  Despite the fact that it was
immediately clear to you, it was clearly not apparent to Scott, and
Scott is one of the brighter people I know.  If he (and several other
very bright people on this list) didn't get it, it might need a little
explaining.

Oh I reckon Scott knows about floating point numbers. It would fit with the general breadth of his knowledge but finding behavioural changes between releases can throw anyone off the scent. I think the 520 behaviour is wrong and should be followed up but it doesn't surprise me that the numbers are different. Nor would it surprise me if the IBM developer said "Too bad, its float, what do you expect?". Of course it would likely be couched in pleasanter terms.

Anyway, that's all. No big deal.

Which is why I'm going to drop it.

Regards,
Simon Coulter.
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