On Fri, 16 Mar 2007, Su, Yu (Eugene) wrote:
> Interesting. Any explanation why sprintf treats 3.5 and 4.5
> differently in rounding?
It is called "unbiased rounding", which has the advantage of not
adding an upward trend to your numbers:
http://en.wikipedia.org/wiki/Rounding
Note that Bill's solution probably only does what you want for
positive numbers. For negative numbers you might want to add -0.5
to achieve the "conventional" symmetric rounding effect.
Cheers,
-Jan
On Fri, 16 Mar 2007, Bill Luebkert wrote:
>
> Su, Yu (Eugene) wrote:
> > I expect
> > print sprintf("%.0f %.0f %.0f %.0f %.0f %.0f %.0f %.0f %.0f %.0f", 0.5,
> > 1.5, 2.5, 3.5, 4.5, 5.5,
> 6.5, 7.5, 8.5, 9.5);
> > will give me
> > 1 2 3 4 5 6 7 8 9 10
> > but instead I get
> > 0 2 2 4 4 6 6 8 8 10
> >
> > How to round a floating-point value to an integer value using (.5) up rule?
>
> I'd add .5 in the next place down :
>
> foreach (0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0) {
> printf "%.1f => %.0f\n", $_, $_ + .05;
> }
>
> 0.0 => 0
> 0.1 => 0
> 0.2 => 0
> 0.3 => 0
> 0.4 => 0
> 0.5 => 0
> 0.6 => 1
> 0.7 => 1
> 0.8 => 1
> 0.9 => 1
> 1.0 => 1
>
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