Re: math.floor and rounding

[KHMan <keinhong@...>]

On 9/20/2010 11:32 PM, Jose wrote:
> I want to round numbers with two decimal digits.
>
> I use  math.floor( n * 100 )  but sometimes I have situations like:
>
> n = 10.20
> math.floor( n * 100 ) -->  1019
>
> My current solution is to always add 0.001 to n, but is this the right
> approach ?

If it's *precisely* 2 decimal places, consider instead to do your 
calculations without any fractions, i.e. use 1020 etc.

Look at it this way -- if you're doing things like that, perhaps 
you are implementing things wrongly. Floating point can only have 
fractions that are the exact sums of 1/2, 1/4, 1/8, etc. If you 
expect *exact* values for things like 10.20, then you're doing it 
wrong.

And if you're doing currency calculations like that, please smash 
your keyboard over your head ;-)

--
Cheers,
Kein-Hong Man (esq.)
Kuala Lumpur, Malaysia