> On 10 mei, 22:32, Frem <freminl

@gmail.com> wrote:

> > Hello,

> > I was demonstrating how easy Tcl is to use (or at least to learn to use)

> > when I was immediately flummoxed.

> > On a Windows XP machine I created a trivial proc:

> > (bin) 289 % proc subtract {a b} {

> > return [expr {$a - $b}]

> > }

> > (bin) 290 % subtract 3 2.2

> > 0.7999999999999998

> > Eh? This was using Tcl 8.5a4. It works properly in 8.4.11. Is this a

> > known bug (sorry if it is)?

> > Thanks,

> > Frem.

> It is working properly in 8.5 as well. The difference between 8.4 and

> 8.5 is that the tcl_precision global is set differently by default.

> In 8.5 the two lines:

> set tcl_precision 12

> subtract 3 2.2

> will give the same result as in 8.4.

> The real reason you get this result however is that floating point

> math is not precise on a computer (0.2 is a repeating binary

> fraction).

People should be reminded with floating point, any fraction that