Re: [Re: RPGILE V4.3 Gotcha]

[Jim Langston <jlangston@xxxxxxxxxxxxxxxx>]

Okay, here is something I would probably use it for.

I sum up all the sales for a given period, since this can be in the 10's of
millions, I'm going to want to use at least 10 digits, right?  We had a
report in RPG II giving wrong results, and I found that it was it was only
using 9 digits, and was loosing 2 places, so I bumped it up to 13 in
my program.  Okay, so I add up all my sales into a variable, and it is
13, 2.  Then I add up all my payables for the same period, and stick them
in a 13, 2 field.  The fields are the right size for the numbers they contain,
and are rather large.  Now, to get a percentage, we divide the amount
of payables over the amount of sales, but we want this as a percentage,
so we want to multiply it by 100.  Something like:
EVAL Percent = (AmountPayable / AmountSales) * 100

In here, we are lucky, we only have 29 total digits.  But, what about the fact
that Percent was based on 4, 2?  (12.35%)  Or what about next year when
it overflows again on me, so I kick them up to 15, 2?

Are these not real world scenarios?  I am, in fact, writing this program now.
And why should I have to use floating point numbers to keep dollars and cents?

The fact is, I'm going to use DIV and MULT just so I don't have to worry about
it.


Ken Sims at SWS Nevada wrote:

> <SNIP>
> I knew about it, and I don't consider it particularly a problem.
> As long as the intermediate result doesn't exceed 30 digits, there
> isn't a problem.  Where the order of operations is flexible, I have
> always coded to keep the intermediate result as small as possible.
>
> If your numbers are big enough in themselves to cause problems in
> the intermediate results, then perhaps you need to be using
> floating point numbers.  If the numbers aren't that big, but the
> fields are, then it sounds like a poor design by somebody.
>
> Ken
> Southern Wine & Spirits of Nevada, Inc.
>
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