RE: TZF - Calculating

Chris Morgan wrote:
> 
> Pierre,
> 
> Nothing is wrong.
> Have a look at
> http://www.bancoems.com/CompLangPascalDelphiMisc-MiniFAQ.htm#Q3
> 
> which discusses floating point accuracy.

This FAQ does not explain the problem completely. One part of the 
problem is that humans use 10-base numbers but computers store them in 
binary format. 10-base numbers with a floating point, like 3.10, cannot 
always be converted with complete accuracy within the limits of the size 
of the real type used. This topic has been dicussed on some of the 
Delphi and Pascal newsgroups; you can check there for additional detail. 
Using the Extended type might solve the problem for this particular 
number, but it will appear again for other numbers. In Delphi 7, Real is 
equivalent to Double. The Currency type might be appropriate for your 
needs depending on the amount of precision that you need. Currency 
supports a maximum of four decimal points, while Extended supports a 
maximum of 19-20 significant digits.

> Cheers,
> Chris
> 
> ----- Original Message ----- 
> From: "Pierre Wittwer" <[email protected]>
> To: <[email protected]>
> Sent: Tuesday, September 09, 2003 12:44 AM
> Subject: TZF - Calculating
> 
> 
> > Hi Topaz-users (or Delphi-users),
> >
> > I have a simple question. I have to convert a string into a
> real.e.g.
> > s = '3.10'  and r is the real.
> > Using Val(s,r,code) I get the real as r =
> 3.09999999999854......instead of
> > 3.10
> > Using the SReal of Topaz I get the correct  '3.10' in the string.
> But for
> > calculating I need the real r
> > What is wrong?  Thank you for your help
> >
> > Pierre Wittwer
> > CH Stans 

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