*From*: "Andreas J. Guelzow" <aguelzow pyrshep ca>*To*: gnumeric-list gnome org*Subject*: Re: ver 1.9.4 use more decimal digits*Date*: Sun, 01 Mar 2009 19:36:25 -0700

On Mon, 2009-03-02 at 07:57 +0800, bill lam wrote:

On Sun, 01 Mar 2009, Morten Welinder wrote:After upgraded to 1.9.4. Diff the gnumeric file with the previous 1.8.3This is deliberate. We need to store enough decimals to ensure that the number we had will come back unchanged. The numberThis is incorrect. The number pairs have the same bit pattern using ieee 754 standard so that they are equal.

The ieee 754 does _not_describe a single bit pattern for every number. You can't even decide whether a number is representable or not in ieee 754 unless you also specify whether you are using ieee 754 single, double, double extended,...

Merely adding more digits does no increase the accuracy.

Adding more digits in the stored number allows transfer of these files from one instance of gnumeric to another that uses a differnet size of ieee 754 floating point number.

There is an article by Kahn who is the driving force behind the IEEE 754 standard, and he got the Turing Award in 1989 for his work on numerical analysis. How Java's Floating-Point Hurts Everyone Everywhere by W. Kahan and J. D. Darcy (March 1998) http://www.cs.berkeley.edu/~wkahan/JAVAhurt.pdf The last page "Accuracy < Precision" From what I can see in your message, previous versions did not deliberately find the minimum digit representation of floating point number within the limit of ieee 754 standard.

Of course not. Especially since there is no such thing as a "minimum digit representation of floating point number within the limit of ieee 754 standard" unless you also specify the size of floating point number. Andreas

-- Andreas J. Guelzow <aguelzow pyrshep ca>

**References**:**ver 1.9.4 use more decimal digits***From:*bill lam

**Re: ver 1.9.4 use more decimal digits***From:*Morten Welinder

**Re: ver 1.9.4 use more decimal digits***From:*bill lam

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