[Info-vax] VMS Software Q1 '23 Update

[Arne Vajhøj]

On 1/28/2023 3:01 PM, Steven Schweda wrote:
>> Consider the case where the numbers represent money.
> 
>     Who cares what the numbers represent?  For example, if you round to
> the nearest integer, then 1.49999 and 1.50001 differ by only 0.00002,
> but one rounds to 1, and the other to 2, so the lame test says that
> they're "unequal".  And 1.50001 and 2.49999 differ by 0.99998, but they
> both round to 2, so the lame test says that they're "equal".  Any test
> which treats a difference of 0.00002 as significant, and a difference of
> 0.99998 as negligible, is, I claim, (obviously) a bad test, regardless
> of what the numbers might represent.

There are some specific rules for money usually about
always rounding 2 digits.

1494 dollars divided by 1000 = 1.494 get rounded to 1.49
                               diff 0.002          not equal
1496 dollars divided by 1000 = 1.496 get rounded to 1.50

1496 dollars divided by 1000 = 1.496 get rounded to 1.50
                               diff 0.008            equal
1504 dollars divided by 1000 = 1.504 get rounded to 1.50

Arne

PS: One should never use traditional binary based floating
     point for storing money instead use some decimal based
     type. But sometimes calculations switch to floating point
     anyway.