[Gambas-user] gb3: incorrect solution to If...Then condition

[Jussi Lahtinen]

Everything seems to work now!

Jussi



On Sat, Apr 28, 2012 at 18:11, Benoît Minisini <gambas at ...1...
> wrote:

> Le 28/04/2012 04:52, Benoît Minisini a écrit :
> > Le 28/04/2012 01:24, Jussi Lahtinen a écrit :
> >> At least the problem is unrelated to sin and cos...
> >>
> >> ? format(0.47942553860420300027 ^ 2 -
> >> 0.22984884706593014129,"#.######################")
> >> - .0000000000000012212453
> >>
> >> ? format(0.47942553860420300027 ^ 2.0 - 0.22984884706593014129
> >> ,"#.######################")
> >> - .0000000000000011379786
> >>
> >>
> >> Jussi
> >>
> >>
> >
> > Hi,
> >
> > OK, I found the bug.
> >
> > The gambas floating point parser incorrectly took into account the
> > leading zero decimal digits.
> >
> > In other words 2.0 was computed as 20 * 10 ^ -1, 2.00 as 200 * 10 ^ -2.
> > Now it is just 2.
> >
> > Consequently, now 2.0 - 2 = 0, and cos(0.5) ^ 2.0 - cos(0.5) ^ 2 = 0.
> >
> > But cos(0.5) ^ 2 + sin(0.5) ^ 2 keeps being not exactly 1.0. Because the
> > gambas algorithm is not the same as the libc algorithm. In gambas 0.5 is
> > computed as 5 * 10 ^ -1, which does not give the exact binary
> > representation of 2 ^ -1.
> >
> > I will investigate...
> >
>
> Hi,
>
> Precision bugs should be fixed now since revision #4688.
>
> ?cos(0.5)^2+sin(0.5)^2
> 1
>
> ?0.5 - 1/2
> 0
>
> Regards,
>
> --
> Benoît Minisini
>
>
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