Re: problem assigning double as defaultvalue

From: Alexander Nickolov (agnickolov_at_mvps.org)
Date: 04/24/04

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    Date: Fri, 23 Apr 2004 23:28:26 -0700

    It's more like ignorance on you part really... This behavior is
    by design - floating point arithmetics is imprecise. You should
    never compare floating point numbers directly (especially the
    results of computations). Have you studied interval arithmetics?
    What about computational methods? You should have studied
    about error accumulation... Anyway, the point is, you should
    compare two floating point numbers by subtracting them and
    comparing the absolute of the difference against your precision
    threshold. If it is under the threshold, the numbers are the same,
    otherwise they differ. 

    -- 
=====================================
Alexander Nickolov
Microsoft MVP [VC], MCSD
email: agnickolov@mvps.org
MVP VC FAQ: http://www.mvps.org/vcfaq
=====================================
"Sascha Herpers" <formefromnews@brainpowered.de> wrote in message
news:c6bavj$a8mkg$1@ID-144102.news.uni-berlin.de...
> > Looks like it gets stored as float somewhere along the line, either in
> > the TLB or in MIDL internal structures. Or, MIDL has problem accurately
> > parsing floating point literals. You see, double gives you precision to
> > about 15 decimal digits, and float provides only 7-8. The number you get
> > from default value is accurate to 7 decimal digits.
> I see. That's probably the reason why casting it to double like this:
> defaultvalue((double) 0.00001)
> gave a totally different result. MIDL seems to somehow misinterprete the
> constant...
>
> Oh well...just another thing I will mark as "don't worry about it, you
> can't change it anyways" kind of thing... :(
>
> Thanks Igor.
> Sash
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