[Gambas-user] Issue 165 in gambas: Arithmetic problem with float

[Jussi Lahtinen]

I know limitations of floats.
I reported this since I found it weird mostly because of it doesn't happen
with equivalent C function with equivalent variable type. So, maybe there
is hiding error.

    double a = pow(2,23);
    printf ("%f\n", a);


Jussi




On Thu, Dec 22, 2011 at 18:19, nando <nando_f at ...951...> wrote:

> Personally, I do not see this as a problem for a float doing this
> calculation.
> Since it is transcendental function, this will happen.
> Plus, float is not 64 bits of precision, it is 52 bits.
> I suggest use INT or LONG
> This type of round-off error goes back to the beginning of time
> -Fernando
>
> ---------- Original Message -----------
> From: gambas at ...2524...
> To: gambas-user at lists.sourceforge.net
> Sent: Wed, 21 Dec 2011 19:12:21 +0000
> Subject: [Gambas-user] Issue 165 in gambas: Arithmetic problem with float
>
> > Status: New
> > Owner: ----
> > Labels: Version Type-Bug Priority-Medium OpSys-Any Dist-Any Arch-Any
> > Desktop-Any GUI-Any
> >
> > New issue 165 by jussi.la... at ...626...: Arithmetic problem with float
> > http://code.google.com/p/gambas/issues/detail?id=165
> >
> > 1) Describe the problem.
> >
> > Dim ff As Float = 2 ^ 23
> >
> > Print ff
> >
> > Gambas gives result: 8388607.99999999 while expected is 8388608.
> > Floating point (64bit) precision should be enough for accurate result.
> >
> > 2) GIVE THE FOLLOWING INFORMATIONS (if they are appropriate):
> >
> > Version: TRUNK
> > Revision: r4297
> > Operating system: Linux
> > Distribution: Xubuntu
> > Architecture: x86_64
> > GUI component: QT4 and GTK+
> > Desktop used: XFCE
> >
> > 3) Provide a little project that reproduces the bug or the crash.
> >
> > Attached.
> >
> > Attachments:
> >       ArithmeticError-0.0.1.tar.gz  4.6 KB
> >
> >
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> ------- End of Original Message -------
>
>
>
> ------------------------------------------------------------------------------
> Write once. Port to many.
> Get the SDK and tools to simplify cross-platform app development. Create
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> http://p.sf.net/sfu/intel-appdev
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