RE: Strange result with exponents...

["Joe Pluta" <joepluta@xxxxxxxxxxxxxxxxx>]

> From: Simon Coulter
> 
> Floating-point behaviour should have been learnt in PGMG 101 and even
> if forgotten should cause a programmer to think "Hmm, floating-point.
> I've heard weird things happen with that. I'd better investigate a
bit".

Okay, I'm going to separate this into two pieces.  First, I'm going to
clearly state that I don't think the difference in results between V5R1
and V5R2 is a big deal.  Since it's been made clear that exponentiation
always used floating point and floating point has always had a precision
limitation, then the fact that there are differences outside the bounds
of the precision limitation is technically okay.

At the same time, I think that if there are changes in the microcode
that effect the result of an operation, it would still be nice to know,
but that's a "nice to know" issue.

Now, on to the other point.  In my opinion, I think it is unreasonable
to expect an RPG programmer to know the ramifications of floating point,
regardless of whether or not they learned it in "programming 101",
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.

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;
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.

Anyway, that's all.  No big deal. 
 
Joe