🚀 go-pugleaf

In article <367A4B0E.CA324425@gisma.de>,
  r.rochow@gisma.de wrote:
> Hi Robert,
>
> thinks about a medium list ( a customer having his acount for 5 years with 20
> movements each month has about 1200 movments ) of cash-acounts, which are to
> be calculated for a saldo. So in most currencys the fractional part has 2
> digits and range from x,00 to x,99. So 0,25 or 0,50 are ( negative ) powers of
> 2 they can be represented in biniary values ( double, extendet ) exactly.
> Values like x,49 or x,96 can't be represendet in double-datatypes -> they
> would result in something like x,489982938739 of x,960021232313. Add two of
> this values and then rounding the result should bring up the correct value.
> But adding hundreds or thousands of this values and then rounding the result
> is a mistake.

Unfortunately I am all to aware of this, at Willis we have to apportion
premiums over many (dozens of) underwriters, and it's a nightmare. All of out
batch programs actually abend if there are control differences, even if only
1 pence!

As some posters wrote, use COMP (-2^63 .. 2^63-1), or consider splitting up
your amounts into separate totals for the integer & fractional parts. It
would extend your range to 2,147,483,647.99 (longint) or
9,223,372,036,854,775,807.99 (comp), which might be enough, and which would
certainly be faster than using BCD.

> The workaround is to round the value each time an operation is done.

Very time consuming, especially if you're using the FPU as every rounding will
save/change/restore the controlword when you're using pure Pascal.

> In my newer c++ programs I use a BCD-Libray ( Money++ from roguewave )
> and I have no problems with rounding error.
>
> So this is the first reason I'm looking for a BCD-Unit for pascal.

Never considered writing some small C++ programs and looking at the generated
code in this BCD library with debug or IDA?

> The second reason is that I get this values from a ISAM-Database and put the
> results to a database ( i use Btrieve 6.15 ). This database is able to deal
> with BCD-Values directly.
>
> Do you have a good BCD-lib/unit or information where get a good BCD-lib/unit
> please let me know.

There are a few long-number units available on the pages of some of the
regular posters in comp.lang.pascal.borland.

Robert
--
Robert AH Prins
prinsra@williscorroon.com

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