A GCC COBOL status report

Posted Feb 16, 2023 7:34 UTC (Thu) by smurf (subscriber, #17840)
In reply to: A GCC COBOL status report by mmaug
Parent article: A GCC COBOL status report

Well, if you want reasonable speed *and* payroll accuracy , today you'd probably use rational numbers (i.e. fractions) as your basic data type. Or 1/1000th cent or whatever (i.e. fractions with a fixed denominator). In fact, that's what I'd expect a reasonable optimizing compiler to convert all these pesky DECIMALs to. Even with inflation / govenments throwing money about like crazy, today's 64-bit integers should remain sufficient for that.

A GCC COBOL status report

Posted Feb 16, 2023 9:56 UTC (Thu) by geert (subscriber, #98403) [Link] (6 responses)

Always using 1/1000th of a cent is overkill, and may even be wrong.
When it comes to money, there are strict rounding rules to follow.
E.g. everything is rounded to a cent. Except for fuel prices, which must use an accuracy of 0.1 cent.
Cash amounts may have to be rounded to 5 cent.
1/1000th of a cent might be useful when calculating the BOM price of your new electronics device, when you order SMD resistors by the container ;-)

A GCC COBOL status report

Posted Feb 16, 2023 15:39 UTC (Thu) by Wol (subscriber, #4433) [Link] (2 responses)

Do you round up or down?

If it's .5, which way do you go (and some places rule that you round to the nearest EVEN (or odd) number).

Okay, fixed decimal doesn't cover rounding rules, but it copes very nicely with correcting different mandatory precisions.

And don't throw significant figures into the mix! When we had the ERM, all calculations had to be done to six significant figures. THAT was fun! Not.

Cheers,
Wol

A GCC COBOL status report

Posted Feb 27, 2023 21:49 UTC (Mon) by nix (subscriber, #2304) [Link] (1 responses)

> And don't throw significant figures into the mix! When we had the ERM, all calculations had to be done to six significant figures. THAT was fun! Not.

Seriously? So for amounts higher than £9,999.99, you started losing precision?! I'd have expected dp at the very least.

A GCC COBOL status report

Posted Feb 27, 2023 22:33 UTC (Mon) by Wol (subscriber, #4433) [Link]

Sorry no.

All exchange rates had to be specified to six figures eactly. Iirc, being about 4 orders of magnitude apart, Sterling to Lire and back wasn't pleasant. Mostly on the display side, not the calculation, admittedly.

And then if you are calculating random exchange rates, rounding before quoting wasn't pleasant either.

Cheers,
Wol

A GCC COBOL status report

Posted Feb 19, 2023 20:15 UTC (Sun) by ssmith32 (subscriber, #72404) [Link] (1 responses)

Stock price quotes are not to the penny. They go out to ten-thousandths of a dollar:

https://www.investopedia.com/terms/d/decimal-trading.asp

So even 1/1000 isn't good enough.

A GCC COBOL status report

Posted Feb 21, 2023 19:42 UTC (Tue) by calumapplepie (guest, #143655) [Link]

1/1000 of a *cent* is

A GCC COBOL status report

Posted Feb 28, 2023 1:38 UTC (Tue) by mrugiero (guest, #153040) [Link]

And then you need to convert currencies. 1ARS is worth U$S0.005. There are cents for ARS too and you need to be able to account for them.
I risk guessing financial institutions do deal with multiple currencies.